Jump to content

Is it normal for roof membrane to leak like a sieve?


Tom

Recommended Posts

12 hours ago, Tom said:

a few areas where the screw didn't take or whatever there are holes going through with no screw, 

Obviously that is not acceptable.  Why have you left it like that? To repair these don't just squirt in silicone. It is possible that the original screw could bite. With quality screws the washer winds itself between the thread and the panel, to seal it.

If that doesn't work the best fix is a non cutting roof screw of larger diameter. If you have a fixings merchant near you, try a visit and be prepared to buy 100 of the right screw.

 

I too think the valley is the likeliest culprit. There are so many possible failures here.

What is the outlet? I would always have a wier overflow as well....to let all the water off the gutter asap.

The slope is  not the greatest issue, but the depth creates pressures on all joints. Just one low spot may allow water over and in.

Link to comment
Share on other sites

42 minutes ago, saveasteading said:

Obviously that is not acceptable.  Why have you left it like that? To repair these don't just squirt in silicone. It is possible that the original screw could bite. With quality screws the washer winds itself between the thread and the panel, to seal it.

If that doesn't work the best fix is a non cutting roof screw of larger diameter. If you have a fixings merchant near you, try a visit and be prepared to buy 100 of the right screw.

 

 

The fixings in question are 230mm long tech screws - going through the 2" counterbatten, through the 150mm composite panel  and in to the z purlin. So essentially you need to aim it right when screwing through from the top, or you will miss the z-purlin, and on a few occasions you hit the steel rafter instead and the self-drilling tip just melts - either way you can be left with a hole. I guess these were not considered a problem at the time as the panels are not meant to be forming the watertight layer, this should be the membrane and final covering - the corrugated sheets.

 

48 minutes ago, saveasteading said:

I too think the valley is the likeliest culprit. There are so many possible failures here.

What is the outlet? I would always have a wier overflow as well....to let all the water off the gutter asap.

The slope is  not the greatest issue, but the depth creates pressures on all joints. Just one low spot may allow water over and in.

 

Can I ask what you mean by the depth?

Link to comment
Share on other sites

51 minutes ago, Tom said:

either way you can be left with a hole

So you adjust starting position and drive another that does connect. In extremis you go old fashioned and predrill a hole.

If yourThen fill the wrong hole as described.try to avoid the bends in thr rail as they are curved and don't accept the drill so well.

 

Professional cladders make these mistakes. Some bodge the repairs and it goes wrong in a few years.

Once water has found a hole, the stream is drawn towards it.

The reason for not using silicone is that most products go hard and shrink over time, especially in daylight.

 

Valley reply to follow

Link to comment
Share on other sites

1 hour ago, Tom said:

what you mean by the depth

Any channel flows according to the depth of water, any gradient and the width. Vitally also the outlet, so an open end or a large downpipe or both.

Even a level channel will drain if there is somewhere for it to go, preferably outside the building.

 

If a gutter has been built level, but has any ups and downs, the lowest edge is where it will run over and that is all the depth of the whole gutter effectively.

If the water isn't escaping fast enough, the gutter will fill until it reaches maximum depth,  then it finds another way.

A full valley creates water pressure on every joint too.

 

I have designed many a gutter and try to put in an extra downpipe every time, and also to have an overflow if possible.

In fact I have redesigned whole  buildings to avoid valley gutters but I don't think you have this option.

 

I don't know what you have for outlets. Photo?

Link to comment
Share on other sites

Thanks @saveasteading . I guess however mane holes there are, filled or otherwise, in the composite panels, shouldn't matter - as we have the (supposedly) watertight layer of membrane above and then of course the final roofing sheets.

 

I just had a word with the builder on the phone to make sure he was planning on coming over tomorrow morning, which he is. I fired an opening salvo re the faults with the roof, to be met with "it's breathable membrane, of course it's going to leak".

 

So, if possible, I need a dose of reality before my face to face with him tomorrow. So far I can see the problems with the work as follows:

 

- membrane pulled too tight allowing water to pool at the battens

- multiple holes all over the membrane (one you can get your hand through)

- membrane not lapped over in to lead valley gutters as the leadwork is too proud

- galvanised nails used on the lead, not copper

- lead gully not stepped (tbh why should it rely on £4 of mastic "leadmate" to keep it watertight when there is the best part of £1k of lead there?)

 

I've just added it up and we've paid just over 7k for this work so far - and that's just for the labour.

What should I realistically be execting from him? Redo? Not sure I want him to considering the standard of his work so far. If he can't/doesn't want to, do I find someone else and give him the bill?

If he reiterates the "it's breather membrane, of course it's going to leak" what is the best response?

 

I'm so effing hacked off with this. We had to pause the build for the best part of a year while this bloke gave us the runaround as we thought he would do a good job - local recommendations etc.

 

 

Link to comment
Share on other sites

15 hours ago, Tom said:

it's breathable membrane, of course it's going to leak".

That's a worry.  You must judge is he ignorant or incompetent?

15 hours ago, Tom said:

multiple holes all over the membrane (one you can get your hand through)

That does make it easy to breathe, if made like a poncho.

 

For your own amusement and knowledge, find an offcut of the breather membrane and make a cup of bowl with it. Staples or paper clips will hold it together. Then fill it and see what you find.

I'm not promising that all products are utterly waterproof, but it's function is to let vapour through while keeping  liquid water out. It has no other purpose.

 

If you know the product then find domf marketing stuff for it.

 

Make a list of problems starting with what he can't dispute, and get him to agree each in turn has to be resolved.

The technical stuff like,  what is a vapour barrier can be last.

 

Have you a robust friend to witness the meeting? Not a construction expert ( or you wouldn't need BH) just a world wise  calm person who could remember what occurs. They can also, if so briefed, keep you calm and on track

 

Link to comment
Share on other sites

A breather membrane is a sheet of material that is installed to the outer side of insulation on both roofs and walls. It allows water vapour to pass through from the inside of the roof or walls, without requiring any ventilation to be installed directly above the insulation layer. It also prevents any form of water, whether it is moisture, surface water or rainwater, from entering the roof or interior space

Link to comment
Share on other sites

The issue with the membrane is it can get damaged when you have folk crawling all over your roof screwing in battens to help them clamber about the roof. A section around our rooflight was in a right mess so I replaced it. We have two breather membranes on ours, one over the OSB sheathing, then an air gap then one over the plywood deck that supports the metal roof. We’ve been quite lucky as our house has remained more or less completely dry. 

Link to comment
Share on other sites

10 minutes ago, Dave Jones said:

completely normal to drip through the nail holes

Interesting. I've never known it to happen.  ?

Perhaps dampness swelled the timber and sealed the holes before any deluge came.

Does that mean every house is at risk of multiple drips  if a tile breaks

Link to comment
Share on other sites

30 minutes ago, saveasteading said:

Interesting. I've never known it to happen.  ?

Perhaps dampness swelled the timber and sealed the holes before any deluge came.

Does that mean every house is at risk of multiple drips  if a tile breaks

 

well. the membrane is pierced by staples/clouts to fix it which make holes. 

Link to comment
Share on other sites

35 minutes ago, saveasteading said:

Interesting. I've never known it to happen.  ?

Perhaps dampness swelled the timber and sealed the holes before any deluge came.

Does that mean every house is at risk of multiple drips  if a tile breaks

 

If the felt isnt pulled tight then the resulting droops keep water away from the rafters - and the holes that are present there. If it is tight then water can find it's way towards the rafters, particularly if so tight so as to be touching the battens across the length. The issue can be exacerbated over time due to dirt build up. 

Link to comment
Share on other sites

On 24/06/2023 at 17:33, MJNewton said:

 

If the felt isnt pulled tight then the resulting droops keep water away from the rafters - and the holes that are present there. If it is tight then water can find it's way towards the rafters, particularly if so tight so as to be touching the battens across the length. The issue can be exacerbated over time due to dirt build up. 

 

it shouldnt be pulled tight. the correct install is for a slight sag between trusses.

Link to comment
Share on other sites

1 hour ago, Dave Jones said:

 

it shouldnt be pulled tight. the correct install is for a slight sag between trusses.

 

Yes, that was exactly my point. Apologies if my wording caused any confusion - I could've explained it better.

Edited by MJNewton
Link to comment
Share on other sites

1 hour ago, Dave Jones said:

 

it shouldnt be pulled tight. the correct install is for a slight sag between trusses.

 

And similalrly, the sag shouldn't be so much as to touch the insulation below..... because that means that vapour droplet forming under the membrane could drip onto the insulation and make its way back into the roof. Ask me how I know. 😔

Link to comment
Share on other sites

  • 2 weeks later...

Update: we had a proper roofer round and he actually laughed when he saw the leadwork. Main problems are:

- seams in the gully sealed with leadmate, this would last a few months according to him. They need proper expansion joints welded in (https://www.t-pren.com/) (or stepped as per @makie 's advice above)

- none of the lead has been oiled/sealed, so it's oxidised - most of the lead needs to be scrapped

- areas where the lead has been dressed in the valleys is done badly, needs to be cut/welded

 

His quote to do the above was in the region of 2k +VAT

 

The membrane still leaks like a sieve but I'm going to get that redone.

 

So, I had a chat with the original guy and he's still adamant that the work he has done is good. He wants building control to come out and have a look - which I have arranged for Thursday - but not sure they will be very helpful or would even be in a position to take a view on the leadwork. Is it a thing that Building Control would take a position on? Also, are there any standards etc that I can quote which shows the requirement for expansion joints or sealing of the lead?

 

On the plus side our floor was poured yesterday. All the drips coming through the roof are actually not so bad now, as having to hose the slab down a few times a day anyway!

 

 

 

 

Link to comment
Share on other sites

  • 5 weeks later...
On 20/06/2023 at 10:19, Barryscotland said:

Our breathable membrane leaked like a sieve and we had to hold off on the screed getting poured till all the slate was on which held us up over a month, roofer said it was down to all the staples that the joiners had used to attach it to the sarking and that it should not leak. We never redid ours which we will probably come to regret. Different setup than yours though as just slate onto sarking

What should it have been attached with?

 

Link to comment
Share on other sites

On 04/07/2023 at 19:12, Tom said:

Update: we had a proper roofer round and he actually laughed when he saw the leadwork. Main problems are:

- seams in the gully sealed with leadmate, this would last a few months according to him. They need proper expansion joints welded in (https://www.t-pren.com/) (or stepped as per @makie 's advice above)

- none of the lead has been oiled/sealed, so it's oxidised - most of the lead needs to be scrapped

- areas where the lead has been dressed in the valleys is done badly, needs to be cut/welded

 

His quote to do the above was in the region of 2k +VAT

 

The membrane still leaks like a sieve but I'm going to get that redone.

 

So, I had a chat with the original guy and he's still adamant that the work he has done is good. He wants building control to come out and have a look - which I have arranged for Thursday - but not sure they will be very helpful or would even be in a position to take a view on the leadwork. Is it a thing that Building Control would take a position on? Also, are there any standards etc that I can quote which shows the requirement for expansion joints or sealing of the lead?

 

On the plus side our floor was poured yesterday. All the drips coming through the roof are actually not so bad now, as having to hose the slab down a few times a day anyway!

 

 

 

 

What happened?

Link to comment
Share on other sites

18 hours ago, CalvinHobbes said:

What happened?

Building control had a look and said was shoddy, but as expected wasn't really in their remit to comment/enforce.

Went back to original guy: came back with a list of excuses which boils down to:

- I hadn't bought him the correct stuff (I bought whatever he asked me - lead, timber etc etc)

- I hadn't supplied him with architects plans of the roof (this roof make-up ie steel rafters, z-purlins etc is what he came up with himself, and deviates from the architects plans which are for a timber roof structure, and anyway, does the architect need to supply drawing indicating the effing lead should be oiled, welded expansion gaps etc??!) 

 

So basically it's my fault as I stupidly assumed that a professional with years of so-called experience who said they could do the job was actually capable of doing the job. You live and learn.

  • Sad 1
Link to comment
Share on other sites

19 hours ago, CalvinHobbes said:

What should it have been attached with?

 

Ours had thousands of staples and also tears where the stapler had hit it. According to roofer it should of been clout nails under the overlap and tile batten going down the roof every how ever often then as it was slated he would snap the batten of as he worked up the roof. Better to flap about a bit then death by staples was his words

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...