Wet patches in new build

The_B_Man

Hi,

I got a garden room built. Basically an L-shaped shed with utility room. There is a wet patch in one of the corners. It changes shape and size. The builder has been pushing me back on this and at one stage said it was just a discolouration (its not).

There's also wet patches inside the doors in both rooms from condensation. He says i don't need to worry about this (I do).

I'm meeting with the builder next week to get it finally sorted as its been going on for 6 months!

I'm just looking for ideas on what is actually required to fix these issues. I've attached photos. There's a damp course underneath which I'm worried has failed. But the garden is on a slight decline. Previously this corner of the garden used to flood during heavy rain, so the builder said he went up about 9 inches. He left a 6 inch gap around the whole shed between the garden wall and the shed wall. I'm thinking is the water coming up from the ground and getting stuck down this gap and moving up and getting in between the bricks. There's no plaster down the side as it can't be reached by hand, so he put some flashing on top to stop rain.

I only owe him a couple of grand and I've no money to go elsewhere so I'm stuck with this fella.

Any advice appreciated.

Cheers

muddle84

Definitely not discolouration. I don't think any of the stains in those pictures is down to condensation either. Thats water getting in from outside somehow. I don't have any ideas how to fix it I'm afraid, you need to find out where the water is getting in!

Can you post also pictures from the outside of those damp spots?

I'm no expert but I think the door should (A) be flush with the outside wall to prevent water gathering on the step and (B) sitting on the DPC to stop water penetrating from beneath.

I think it's usual practice to put silicone under uPVC doors to help prevent water ingress underneath. If this wasn't done here, it may be an additional factor. If the door visible from the outside (with the drain beside it) in the second photo is the utility room then rain would gather on the bit where it's inset, and potentially penetrate under the door either by soaking through the concrete like a sponge (concrete is porous) or leaking directly underneath the frame. If the door is inset there should be a cill (or something) to bring the water away from the door— water can't penetrate a weak spot if the water isn't there...

Good luck with the builder— sounds like he keeps just saying there's nothing actually wrong, so you'll need it. If he won't do anything to fix it then unless you want to either accept the damp patches or take the hit on remediation it'll mean a court case— might come in at under €2k (small claims court) and almost certainly under €15k (District Court) so at least going to law would be relatively painless.

Around the doors you could try and get silicone underneath if possible to stop water ingress, and paint/seal the step to stop water soaking into the step. That's probably less of a fix and more of a temporary mitigation though.

The Continental Op

Old trick to see whats going on. Tape a sheet of clear polythene sheet over that affected areas (try and seal it with tape all the way around). Any condensation on the concrete side of the polyethene can only have come out of the concrete.

I'd take a guess that the DPC is 100% OK but it doesn't come up far enough on the outside or put another way the soil is too high and covers it. Maybe dig out and seal the edge of the concrete or better drainage outside would be my answer at this stage.

Under the double doors might need sealing properly to fix that area but moisture could be coming from deeper down.

Furze99

A sketch of new construction might help. Is this built on to existing house and is this damp spot where they meet? Should be adequate flashing etc to stop water ingress at junction of buildings.

10-10-20

Yes, need a photo of the opposite side of those double doors. I'm wondering if it's what ShedHead1 said and that the doors just aren't sealed and that damp spot to the left is just where the run-off is appearing.

I had French doors installed direct down on the concrete threshold here - very bad install job. I had to create a run-off on the concrete to direct the rain away. Even at that it wasn't ideal and I ended up pulling the doors out and installing a PVC threshold and new doors.

The_B_Man

Here's photos of the outside.

There's a grate in front of the door. On the right, as u look into the shed from outside, there's some flashing. Under here, they put a perforated pipe to try fix the water getting in, in case it was coming up from that side. That pipe feeds into the pipe under the grate.

The French doors wouldn't close properly so they had one of the lads adjust them. At this point there was already Tec7 on the inside and outside. He then put Tec7 over the screws at the bottom of the door frame, in case water was getting in there.

The Continental Op

Do we know where the DPC runs including the one for the wall?

sydthebeat

Not the first builder to mess up constructing a threshold and won't be the last

The problem here is the doc isn't fitted properly (or at all) and water is being blown in under the door when it rains.

No amount of tec7 or silicone will fix this.

Most likely no edge strip insulation either to prevent the thermal bridge.

The Continental Op

https://www.boards.ie/discussion/comment/120075026#Comment_120075026

I'm interested to know where you think the water is being blown under? I can't see any gaps.

sydthebeat

Theres a gap between the aco drain and the step, plus the step itself is fully masonry. So while the plaster will provide some protection , its not completely water proof. Any rain blown onto the door will trickle down onto the step and remain there due to its horizontal nature. This will continue to seep into the structure through capillary action.

if plaster was water proof there would be no need for DPCs

The_B_Man

Here's photos of the DPC from during construction.

Some of the photos seem to be upside down but basically they put down DPC for the whole floor on the inside, as can be seen coming up the walls, which they then cut the excess off. For the external bricks, they ran a layer on top of the base layer of brick, which would be in line with where they built the door frame.

The_B_Man

On the advice of a friend, I put a hose down the side (where the flashing is now) and left it for 15 minutes. I know thats more water than you'd get from rain but it absolutely soaked the inside, so I only did it the once.

So after that, he put the flashing up, but I mean, that side clearly isn't waterproof!! 🤣

Furze99

https://www.boards.ie/discussion/comment/120075312#Comment_120075312

Well it's a 9" cavity block wall as I see it in other photos, so you're basically relying on the exterior render to keep rain out. And that maybe the source of your issue, rain soaking through the render and then working it's way down to pool at the base.

It's not a great form of construction, grand for a shed but less so for a habitable space. Was used once though widely enough for a period, 70s?

10-10-20

Yeah, so I think the water's hitting the wall and door threshold and then dropping down to the DPC and tracking along it. Makes sense to me.

That door threshold finish is exactly the same as what I had, except I had a double-leaf, and the damp came over the inner leaf and into the house under the floor. It's a pitiful finish on what is otherwise a nice job.

C. Eastwood

https://www.boards.ie/discussion/2058278398/wet-patches-in-new-build

Hi The_B_Man

Unfortunately you have very serious problems in your new build.

To rectify the problems will require expensive necessary remedial works to be carried out.

If you do not have the complete necessary remedial works carried out, your new build will always be very damp and unsuitable for human habitation.

I have not seen worst building works in decades.

There are many breaches of the Building Regulations apparent, in your photos.

The Building Regulations have 5 Purposes:- Health, Welfare and Safety of persons, Access for persons with disabilities, and Conservation of Fuel and Energy.

The person or persons who carried out the works as seen on your photographs, are not Builders- they are a bunch of Incompetent negligent Langers.

The bad thing is that, from the incompetent building works carried out, I don’t believe that you will be able to get these plonkers to pay for the necessary Remedial Works.

You have received advice above in the forum to your problems, some of same is good and some of the advice is not helpful to you.

I will give you professional advice here below, but please note that some of the advice I have given to people looking for same in this forum, - is removed forthwith. So please copy my advice here immediately and save it.

The first task that you must do is retain one of the following:-

1. Chartered Building Surveyor
2. Chartered Building Engineer
3. Chartered Civil Engineer
4. Architect.

Please let me know your thoughts on my advice above.

Regards

C. Eastwood.

The Continental Op

I think we need to remember the OP stated this is a garden room "Basically an L-shaped shed with utility room" which is not the same as a house extension.

C. Eastwood

https://www.boards.ie/discussion/comment/120078620#Comment_120078620

Thanks Continental

I understand that

The room will always be saturated with rising dampness and ingress of rain water.

The_B_Man expected a shed and utility room which will not be effected by rising damp and ingress of rainwater.

It will be very expensive to carry out all necessary remedial works to prevent the dampness.

It would have been very simple to carry out good proper building works during construction- to prevent the terrible dampness

It is disgraceful building.

The Continental Op

I don't see rising damp as a problem in the slightest there's a perfectly good dpc in the floor.

Ingress of rain does however seem to be 100% the issue.

It might sound mad but I'd consider several options including, external insulation, cladding (wood or uPVC) and even waterproofing the outside of the wall. If the outer face of the wall can be kept dry damp can't get in by that route.

But then there is the water getting under the door. Again waterproofing the area or preventing water getting near it would be my option.

C. Eastwood

https://www.boards.ie/discussion/comment/120078841#Comment_120078841

What is under the floor is not a DPC - it is a DPM (Damp Proof Membrane).

The DPC in the 225 mm wall is 225 mm wide. It should be 500 mm wide and projected in 275 mm and be turned down and lapped100 mm and bonded with the DPM in the floor to prevent rising dampness- this is not done and there is no continuity between the DMP and DPC - which MUST be done to prevent rising dampness. This is essential.

F07D0C09-9A2D-4A78-A97B-FF0382055CE2.jpeg

If all the €€€€€€items you listed above were all applied collectively to the outside face of the external wall- it will never arrest this rising dampness.

The Solid 100 solid concrete blocks under the door frames must be removed - and correct detailing carried out to prevent rainwater pouring in under the door frame cill.

Outside the single door, the ground level must be 150 mm below the DPC to prevent dampness and it is not 150

It is impossible to waterproof the existing detail under the doors - because water and dampness is highly intelligent.

The Continental Op

https://www.boards.ie/discussion/comment/120079073#Comment_120079073

LOL OK I'll leave it at "water and dampness are highly intelligent". Probably similar to your intelligence level.

I'm sure your googling and quoting of regulations for houses are word perfect but must be dones on a "garden room" seem very unlikely because I doubt anyone is going to be paying for them. Expedients and patches are more likely the order of the day.

The_B_Man

Yes its a garden room and shed but I'd still expect it to be built to the same standard as any other building when it comes to rain ingress.

It won't be habited, but we've already started joking with my daughter that she'll be living there when she's 18 due to the housing crisis, so i mean there's a possibility that could come true!

Besides, its a brand new build, built from scratch. Rain shouldn't be getting into an outdoor building. The builder should have done a better job but he's obviously a chancer.

He said he'd ring me tomorrow. I don't think he has a clue where to even start troubleshooting.

https://www.boards.ie/discussion/comment/120081046#Comment_120081046

The crappy €500 flat-pack wooden shed I got from Argos 6 years ago has less water ingress from driving rain than, and I don't see why the expectations of a block built shed costing a small fortune should should be any less than that. Any building has one primary function: effective shelter from the elements, and it sounds like this garden room has failed that very basic test.

And that's ignoring the harsh reality that with the decade long train wreck that is the housing crisis, a garden room in a parents back garden could easily be the only prospect of many children having their own space before they're 30.

https://www.boards.ie/discussion/comment/120075550#Comment_120075550

My house is built the same way, 40 years old & I've been in it for 20 with no hint of water penetrating the render anywhere. Ditto the entire estate: there's nothing inherently wrong with it, if it's done right.

The render does look quite thin, so maybe that's an issue? It looks more decorative than functional. The render + pebbledash on my house is at least an inch thick. Some sort of cladding might address the penetration through the render at least. Battens & cement board maybe?

The Continental Op

https://www.boards.ie/discussion/comment/120081341#Comment_120081341

But you haven't come up with a solution and keep going on about raising damp. There is not an economic solution other than bankrupting the OP or the builder that will fix the problem according to building regulations.

With water coming in the way it is from the hose pipe test I don't see how having the DPM and DPC correctly installed would help. I think the water is getting through the wall going down inside the cavity blocks hitting the DPC then coming out. The fact its rendered probably means the small amount of protection from water ingress that gives means that once the water is inside it pools at the bottom inside the cavity blocks and comes out the easiest route on inside the room. The detailing around the door is another issue which we have a good reason for but no fix it solution.

If there was no DPC (then we could talk about raising damp) I suspect while the wall would be damp there would be less of a problem as the water through the wall would pool down below the floor level before draining away. That isn't a solution but might help explain what I think the problem is.

The bl00dy cavity blocks are the problem along with the DPC being all at the same level meaning the water sits at the bottom when it gets in. A normal cavity wall would have a separate DPC for each side of the cavity so water getting in would drain out below the DPC.

chooseusername

The floor damp proof membrane appears to stop short of the threshold and is not bonded with the wall damp proof course.

The wall d.p.c. that is supposed to continue across the threshold appears to have been discarded. Ideally the floor d.p.m. should lap over the wall at the d.p.c course and the wall d.p.c. laid on top. The floor was laid after the walls were built up, so this did not happen. It doesn't matter how far up the wall the floor d.p.m. comes, if it doesn't tie in with the wall d.p.c. you will get damp at the floor/wall junction.

dpm.jpg

The exterior render looks to me to stop about 4" above the d.p.c. and the render on the plinth is very thin, if this is the case and bearing in mind it's built with cavity blocks it will result in dampness.

dpc.jpg

standardg60

https://www.boards.ie/discussion/comment/120081555#Comment_120081555

There are 3 separate issues imo. The wall where the OP did the hose test is not rendered, it's just bare block because it was built too close to the boundary wall. After the hose test the builder installed flashing in the gap between the two which is worth a pic in itself.

As others have said there is no seal between the dpm and dpc which is also an issue, damp will always ingress here. At the threshold the dpm should have been extended out to the where the door is and then brought up to meet the frame. Might be possible to knock out the section of block between the dpm and frame, install another piece of dpm and re concrete.

The_B_Man

So the 1st photo with the flashing is in the right as you look at the the shed drom outside. The flashing goes about halfway back, with the idea that the neighbours shed will act as a cover for most of the rain at the back.

The 2nd photo is the otherside, which has no perforated pipe or flashing. You can see how the brick is left untouched. However there is no water ingress on this side, somehow!

The flashing was added afterwards. This was done by adding a single column of bricks and cementing onto the finished dashing (both sides has this wall to stop the kids getting down the side), then putting some wood at an angle and attaching the flashing to the wood. As i said, its only halfway deep at best. Maybe even a metre or so.

10-10-20

So that flashing isn't embedded in the wall, it's just adhered to it?

Still stihl waters 3

What cowboys are still using 9 inch cavities, a timber frame stud would be a better option than them

mickdw

A single leaf build with a flush threshold with much of the external brought up to internal floor level, (not just a ramp area) is going to be a mess.

I don't see an easy fix. Had you any professional input at all prior to building?

https://www.boards.ie/discussion/comment/120083619#Comment_120083619

9 inch cavities are fine if detailed properly: I'm 20 years living in a house constructed of cavity blocks with no issues of damp or water ingress. The OP's contractor didn't bother their @rse rendering half of one wall at all, never mind doing an adequate job of it. And the DPC/DPM/Doors would likely cause issues no matter what construction method was used. There's no construction method is idiot-proof.

But yeah, cowboys. And yeah, timber frame + cladding would address at least one of the issues (although possibly making other issues worse).

On the assumption that the builder isn't going to fix the issues properly, and also assuming the OP isn't going to spend €10-15k getting them fixed properly, the mitigation measures I'd suggest would be:

On the unrendered wall: 2x1 treated vertical battens + cementitious fibreboard cladding. Render the boards as much as practicable, but even the unrendered boards should protect the unrendered part of that wall.

For the doors: retrofit a sill of some description. It won't be perfect unless you're willing to spend several thousand euro replacing the doors. But even a layer of plastic adhered to the ground & siliconed all around will reduce the amount of water soaking into this part.I personally would start off by putting epoxy resin for a swimming pool on the bottom + part way up the sides and then get as much silicone as possible between the door frame and the ground.

Neither of these are anything close to perfect/best practice. But they're things that can actually be done at reasonable cost, and might (or might not) be good enough.

C. Eastwood

https://www.boards.ie/discussion/comment/120084663#Comment_120084663

It is very evident from all the many photos above -that the DPM below the floor is not lapped with the 225 mm DPC in the 225 mm wall.

This lapping is carried out to prevent Rising Dampness.

See diagram

E8650B58-EF79-4678-A6F2-E6E49FE5D5A0.jpeg

This is the worst and most important incorrect detail which must be fixed.

It is impossible to stop the rising dampness in the concrete floor- if this issue is not rectified.

The_B_Man

This is grim reading.

I spoke to the builder today and he said he'll be around Wednesday morning so we'll see if he actually turns up.

I'm gonna push him to fix it all but, knowing what he's like, he'll try do a quick fix. Not sure if I should ask him to do his own investigation or tell him what was said here and he needs to redo the DPC and DPM. He'll probably tell me he'll put a decline in the front step so the rain gets taken away from the door!

Am I right in thinking the minimum for a permanent fix is to rip out the doors, dig up the threshold, redo the DPM and DPC by lapping them properly, and then maybe add some tanking to the steps? Or maybe the decline as I suggested above?

Basically, what would you accept as a bare minimum if it was your build?

Thanks for all the help as well, folks.

Cheers

standardg60

Doubt there's much can be done easily about the dpm/dpc join OP, it's not the worst issue anyway. Perhaps the skirting could be removed and the join sealed with mastic.

The gaps between the building and the boundary walls need to be sealed up with flashing at the bottom of the render, you can see how much water is starting to gather in the non flashed side already. The other wall beside the neighbours shed looks like it's not rendered at all past a metre or so, and should be covered with some sort of water proofing.

The floor inside the threshold is neither sealed vertically from the outside nor underneath, which is why i suggest digging that section out and replacing with dpm all round and concreting.

Edit to add that if you still owe them a couple of grand and you have no luck with him you could be better off calling it quits and getting someone else who actually knows what they're doing.

C. Eastwood

https://www.boards.ie/discussion/comment/120086292#Comment_120086292

My opinion, after inspecting your photographs, is that the builder is a Plonker with very little knowledge of the Building Regulations or Building Science, Construction Details etc, and will not have a clue what errors have been created - and therefore will not know what remedial works must be carried to remedy these defects.

To arrest rising dampness in the floor-the concrete floor must be opened up and the DPM must be chemically bonded to the 225 mm PVC DPC in the walls.

The Doors and frames must be removed and 2 courses of solid concrete blocks, below the DPC at the door opes must be removed, and the DPM and DPC must be rectified at these opes, etc

Furthermore, the thresholds / cills of both the single and double doors constitute tripping hazards in accordance with the Building Regulations, and must be lowered.

You need to retain a Chartered Construction Professional with Professional Indemnity Insurance to carry out investigative works on the existing construction, and prepare a Specification of Works necessary, and get agreement with the builder that he will carry out all of the necessary works to the satisfaction of your Construction Professional.?

When the remedial works are completed and certified by the Consultant, - all the problems should have been resolved.

The Construction Professional is obliged to ensure that all works must be in compliance with the Building Regulations and furthermore, on completion, they must ensure that there is absolutely no rising dampness and no ingress of rainwater to your building, etc.

Mellor

https://www.boards.ie/discussion/comment/120075298#Comment_120075298

The DPC is in the wrong position.

The DPM is cut at the floor level.

Those two issues are the main problem, and means that the wall floor junction is not waterproofed. Water can flow from the outside to the inside with little restriction. This is not up to building regs and a huge issue to re-do to a good standard. People saying that's not a big issue don't seem to understand how water proofing works.

Whatever solution you do with be "as good as we can" type solution.

In fairness, there's a few contenders for the title of "worst construction detail" in the OP's build.

But yeah, safe to assume that the solution isn't going to be perfect or anything remotely close to it— perfect is effectively unachievable at this stage without demolition & rebuild.

The_B_Man

I spoke to him just now. He said rain is getting in behind the dashing on the outside door frame. He's gonna remove the dashing and plaster all around like the step.

He's also gonna take the whole door off and reseal it.

I asked him about the DPM and DPC not lapping and the flat step letting resting rainwater in, but apparently that's not it and he's been around long enough to know whats wrong. I pushed him on it again and said I'd shown pictures etc and, no surprise, he dismissed it. Said you always get builders who say stuff like that. Also said the step is waterproof. There's waterproofing mixed in with the plaster.

He'll be back Monday and I'm gonna prepare a list of photos to show him, coz i dont think replacing the door will fix it. He also said he'll dig up the concrete in the corner to investigate and if there's water under it, he'll do a French drain to prevent the water getting to it. More hiding the problem rather than fixing it tbh.

eusap

@The_B_Man where did you actually spray the water?

The_B_Man

The right side of the shed, as you look at it from the outside. I left the hose sitting on top of the flashing. I think the hose was pointing directly at the upper bricks. I thought the water went through the concrete between the bricks (as there was gaps where the concrete wasn't out as far as the brick) but the builder told me the water would have run down the wall, hit the damp course, and went in.

C. Eastwood

https://www.boards.ie/discussion/comment/120092946#Comment_120092946

Hi The_B_Man

Note that the walls do not have to be taken down and the floors do not have to be removed.

See the photo below:-

6BD9BEF1-00C3-4E56-BD73-9478DA79E74D.jpeg

This photo shows the 225 mm PVC, DPC (Black) on top of the solid concrete blocks rising wall below the DPC.

Your builder should have used a 450 mm wide PVC, DPC, and allowed it to project inside the wall, to be folded down 100 mm min over the Polyurethane DPM under the floor, where the DPM is turned up the inner face of the external Cavity Block walls.

Laying the 225 mm DPC was where the Error was first commenced. Since the 50’s every person in the building industry ( except your builder) is aware that the DPM must be lapped 100 mm with the DPC.

As can be seen in the photo below which confirms that the concrete floor is finished at the same level as the DPC in the wall. This is a correct detail.

76680633-ED80-4184-B748-4E2B4B9450F9.jpeg

The next photo below is proof that the DPM is turned up the wall as it can be clearly seen at the bottom of the photo.

The DPC is also visible in the photo:-

717CCD86-EB5F-47E9-9DBF-A141E9F08F58.jpeg

From the photos provided by you it is evident that the DPC is not lapping with the DPM by 100 mm. In fact there is no lapping whatsoever.

The skirting boards must be removed and the perimeter of the concrete floor opened up to expose the edge of the DPC and the top of the DPM. This is a simple task.

The DPM must then be Chemically bonded to the DPC to prevent rising dampness.

If this is not completed then there will always be rising dampness at this junction.

It is a Building Regulations that the finished external ground level must be 150 mm below the DPC.

This is shown in the diagram below from the Homebond Manual

1E8D875A-434E-4729-AB12-CBE05C450F7F.jpeg

The diagram shows a Cavity Constructed wall. Your wall is a Cavity Block constructed wall, and it is vital that the outside footpath is min 150 below the DPC, (except at door opes).

You stated above as follows:-

I asked him about the DPM and DPC not lapping and the flat step letting resting rainwater in, but apparently that's not it and he's been around long enough to know whats wrong.

Not alone is the builder a Langer, he is now telling Porkies. Therefore you need a Chartered Construction Professionals to deal with this pig headed attitude. You have wasted enough of your time and are under a lot of stress dealing with this Moran.

You also stated that the builder - “Also said the step is waterproof. There's waterproofing mixed in with the plaster.

This ridiculous statement is beyond belief.

This is absolute rubbish. The Cill/ threshold of the PVC door frames are resting on top of the 2 rows of 100 mm solid concrete Blocks in the photo below

CB26706D-A95D-40A1-959E-F13BEF9E843B.jpeg

Nothing will waterproof this.

It is very evident that the DPC in the photo was cut off and the door frame is resting on the solid concrete blocks, and the DPC is missing under the door frames. Unbelievable!!!

Both of these 2 courses of 100 mm solid concrete blocks MUST be removed, and a cast in-situ concrete step must be installed under the door frame, with correct DPM and DPC detailing.

The Door Frames must be lowered so that the Thresholds do for create a tripping hazard.

Your lad Delboy Trotter, will not have any glimmer of how to do this.

Do not waste any more of your time with him. Engage a Chartered Construction Professional.

Still stihl waters 3

Waterproof for plaster isn't waterproof, it's water resistant, it helps repel water but under the correct conditions it will let water in

Furze99

https://www.boards.ie/discussion/comment/120086292#Comment_120086292

"Basically, what would you accept as a bare minimum if it was your build?"

If it were me, I'd push for your builder to put on a good thick exterior render. 9" cavity block is often used for sheds and the like but will rely on the render to stop rain soaking in and dripping down to pool at the base. May well also appear as damp spots higher up. I had a similar problem on a self built shed, driving rain came before I had time to tackle the rendering, amazing the amount of water that will get through. So for a good thick exterior render, you need three coats starting with a strong scud coat and then two sand/lime/ cement render coats of a weaker mix. The first of these coats is scratched to allow the final coat a grip. Decorative stone only goes up on the final coat, but I think a nap finish with paint will help you. Use water proofer in the mixes and then when ready, at least two good coats of a good quality exterior wall paint. Problem should be largely solved then. I wouldn't obsess about rising damp unless you're living in a bog but you can assess that after you've dealt with rain water soaking through. That's what I do anyway.

10-10-20

https://www.boards.ie/discussion/comment/120095815#Comment_120095815

Would waterproofer in the render layers also not stop moisture from the cavity blocks from passing outwards, causing condensation within the cavities and hence more moisture landing on this already questionable DPM and probably ending up back in the room? Otherwise in agreement.

Mellor

https://www.boards.ie/discussion/comment/120092946#Comment_120092946

He’s around long enough to know what’s wrong?. Well a few days ago he thought it was discolouration. There are two explanations. Either he hasn’t a clue about building. Or he’s actively lying to you. Not sure which is worse.

The water proofing must lap. No exceptions. This is basic first year student/apprentice stuff. I wouldn’t being giving this guy another penny.

the spiel about the door is also not true. The first wet patch was away from the door. I’d pick a different wall entirely from the door. One that is rendered. And soak the wall at ground level (below DPC). Let’s hope it doesn’t get in, but it might.

Mellor

https://www.boards.ie/discussion/comment/120094323#Comment_120094323

I agree with most of this, but for the sake of completeness, and to avoid giving the builder an excuse to hang to.

The DPC doesn’t have to be 100mm wider that the wall, and turn down. It has to lap 100mm, this can also be achieved by lapping the DPM horizontally with the DPC, as long as it laps. As shown in the homebond detail you posted.

It also needs to be full width inc. render not just block width.

Furze99

https://www.boards.ie/discussion/comment/120096796#Comment_120096796

It would appear that most of the moisture in his walls is soaking in from the outside. If there's normal humidity inside and some condensation etc., that can be alleviated by ventilation.

10-10-20

https://www.boards.ie/discussion/comment/120098046#Comment_120098046

Yes true, but I still think it could be a concern as there is no path for trapped moisture within the walls and may not be a VCL either.

C. Eastwood

https://www.boards.ie/discussion/comment/120097621#Comment_120097621

Thanks for your reply Mellor

I agree that the DPM should be built in to the wall under the DPC.

However, if the builder had built-in a 100 mm wider DPC, which could have been turned down and bonded 100 mm to the upturn of the DPM - there would not be a rising dampness issue, except where there is no DPC over the solid concrete blocks inside the door thresholds.

Furthermore, it is evident that the floor is level with the DPC in the wall. The Belcast at the base of the dashing/ plaster above the smooth plaster plinth must be at the same level of the DPC to mask the horizontal crack which will appear at DPC level, and also to have the rainwater pouring down the wall to drip off at DPC level. Unfortunately Delboy has this Belcast approx 180 mm above where it should be.

I fully understand all details of DPC’s DPM’s Radon Barriers and Tanking etc.

My advice given to The_B_Man is in relation to the existing problem pertaining to his new build.

There are so many problems there - I have not mentioned a Radon Barrier.

The only way to NOW get the DPM 100 mm lapped with the DPC in the wall is to demolish and rebuild the cavity block wall.

Demolishing the existing cavity block wall is unnecessary and incorrect and very expensive and furthermore it would be unethical to request or expect the builder to do this, when there are many solutions to fixing the existing unconnected DPC/DPM.

I specified a solution of how to remedy the rising dampness in the existing build in my post above on 11-1-2023 @ 2.02.

In many builds there are reasons why a builder will need to construct the external walls before pouring the Concrete Floors. One solution for this is to build in a 1m strip of DPM in to the wall at DPC level and fit the PVC DPC on top of same and this gives a 225 mm lap. However the builder must apply a 450 mm wide strip of PVC DPC which must project 225 mm in over the strip of DPM. This is to protect the flimsy 1200 gauge DPM from being damaged during construction. Mastic would be applied where the DPM under the floor meets with the 1 m strip of DPM built-in to the wall.

Unfortunately The_B_Mans - Delboy the Builder is a little short of knowledge of these details.

There are thousands of houses in Ireland being refurbished with the timber suspended floors replaced with concrete. In these properties , to prevent rising dampness, the new DPM must be chemically bonded on to the original existing DPC in the walls. This is a simple task.

This is the same scenario pertaining in The_B_Mans house.