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Child Item

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

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[Deleted User]

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).

[Deleted User]

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.

[Deleted User]

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.

C. Eastwood

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

What about Dry Rot of the Skirting boards. Ventilation of the Utility cannot prevent this.

What about the musty odour from Dry Rot.

Furze99

https://www.boards.ie/discussion/comment/120100015#Comment_120100015

He could use tiles.. surely the impact of rising damp very much depends on the nature of the ground and drainage from the area etc. His walls have a DPC if I recall from the photos and the concrete floor has a DPM. The detail of the relative position of these is incorrect but is he not looking at a relatively small contact area between the sub floor and the blockwork lying above the DPC? If the house is built in a bog or a hollow where surrounding drainage gathers maybe he has a problem but otherwise? Just wondering?

standardg60

https://www.boards.ie/discussion/comment/120100094#Comment_120100094

I agree, too much is being made here of the lack of joining of the dpm and dpc. The amount of damp which is going to seep up here is minimal compared to the threshold detail where there is no dpc under or separating the outer or inner parts either side of the doorframe.

Also, when the OP ran the hose in the gap between the building wall and boundary wall, it is likely to me the water pooled up above the dpc and then came through the unrendered wall. Any water in this gap has nowhere to go as both sides have been bricked up, and on the unflashed side is already pooling. Has no-one any comments on this aspect?

C. Eastwood

https://www.boards.ie/discussion/comment/120100094#Comment_120100094

Why should the OP have to pay for the supply and fitting of Tiles or any other works because of Delboys total incompetences.

The OP accepted Delboy as a Builder because Delboy declared himself as a Building Contractor.

It the tiles are fitted up against the Shirtings- the skirtings will be damaged and decay by Dry Rot.

If the skirtings boards are removed and the tiles fitted out to the plaster of the walls, and allowing space at the walls for expansion of the tiles, and the skirtings boards refitted.

Unfortunately, capillary action will cause moisture under the DPM / DPC to rise up through the gap between the two, which in turn will increase the Moisture Content of the skirting boards above the Dry Rot safety line. The skirting boards are contaminated with Dry Rot spores, which will germinate with the increased moisture and lack of fresh air in the gap between the back of the shirting board and the plaster - and Dry Rot will destroy the skirting boards.

This is all basic Building Science.

It will cost the OP a lot of money going forward on an ongoing basis - if the builder does not carry out all necessary remedial works.

Delboy the builder is responsible for all of this disgraceful building works, and he should be made carry out all necessary remedial works. - under the supervision of a Construction Professional with PI Insurance, who will certify the completed remedial works.

C. Eastwood

https://www.boards.ie/discussion/comment/120100233#Comment_120100233

You asked- “Has no-one any comments on this aspect?”

There is not enough evidence to give a professional opinion on this.

standardg60

https://www.boards.ie/discussion/comment/120100527#Comment_120100527

The OP posted a pic of water pooling in the gap between the walls and the wall of the building only rendered as far as the boundary wall.

What is your professional opinion on this?

Furze99

https://www.boards.ie/discussion/comment/120100500#Comment_120100500

What's the fascination with skirting boards in a 'garden room'? We don't have skirting boards in any of our utility rooms for example. They're not a necessity. Puzzled.

muddle84

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

I don't see how ventilation will solve any of the problems shown. If its just condensation then yes ventilation will solve it. But the water is soaking through the exposed block along with all the other leaks. Ventilation won't do anything for leaks!!!

Timfy

https://www.boards.ie/discussion/comment/120101844#Comment_120101844

Not to cast any aspersions on the OP who appears to be quite genuine but a lot of "utility rooms" and "garden sheds" have sprung up around here and are now commandeering €150-€200 per night on Air B&B!

Mellor

https://www.boards.ie/discussion/comment/120099983#Comment_120099983

I agree that chemically joining the two is the only solution now. I was only highlight the various right ways for OP so the builder didn’t try to weasel out of it by misrepresenting a different detail.