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Wet patches in new build

  • 05-01-2023 11:30pm
    Registered Users Posts: 7,856 ✭✭✭


    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.




  • Registered Users Posts: 1,673 ✭✭✭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!

  • Posts: 0 [Deleted User]

    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.

  • Registered Users Posts: 5,970 ✭✭✭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.

    Wake me up when it's all over.

  • Registered Users Posts: 9,508 ✭✭✭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.

  • Registered Users Posts: 6,311 ✭✭✭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.

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  • Registered Users Posts: 7,856 ✭✭✭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.

  • Registered Users Posts: 5,970 ✭✭✭The Continental Op

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

    Wake me up when it's all over.

  • Subscribers Posts: 40,566 ✭✭✭✭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.

  • Registered Users Posts: 5,970 ✭✭✭The Continental Op

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

    Wake me up when it's all over.

  • Subscribers Posts: 40,566 ✭✭✭✭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

    Post edited by sydthebeat on

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  • Registered Users Posts: 7,856 ✭✭✭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.

  • Registered Users Posts: 7,856 ✭✭✭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!! 🤣

  • Registered Users Posts: 9,508 ✭✭✭Furze99

    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?

  • Registered Users Posts: 6,311 ✭✭✭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.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood

    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.


    C. Eastwood.

  • Registered Users Posts: 5,970 ✭✭✭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.

    Wake me up when it's all over.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood

    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.

  • Registered Users Posts: 5,970 ✭✭✭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.

    Wake me up when it's all over.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood

    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.

    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.

  • Registered Users Posts: 5,970 ✭✭✭The Continental Op

    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.

    Wake me up when it's all over.

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  • Registered Users Posts: 7,856 ✭✭✭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.

  • Posts: 0 [Deleted User]

    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.

  • Posts: 0 [Deleted User]

    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?

  • Registered Users Posts: 5,970 ✭✭✭The Continental Op

    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.

    Wake me up when it's all over.

  • Registered Users Posts: 3,379 ✭✭✭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.

    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.

  • Registered Users Posts: 4,050 ✭✭✭standardg60

    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.

  • Registered Users Posts: 7,856 ✭✭✭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.

  • Registered Users Posts: 6,311 ✭✭✭10-10-20

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

  • Registered Users Posts: 984 ✭✭✭Still stihl waters 3

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

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  • Registered Users Posts: 23,083 ✭✭✭✭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?