Single glaze - leaking frame, rotten membrane

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89 posts

Master Geek

#1087039 11-Jul-2014 12:18

It is unlikely that the exterior joinery is leaking or that the decay evident was caused by condensation. If it was condensation then your jamb liner would rot from the top down and your photo shows the top surface to be nearly unscathed.

What is most likely is that the junction of window to cladding is leaking at the jamb and sill.

Sill flashings were not a requirement for direct fixed fibre cement claddings until 2004. Prior to that James Hardies literature said something like - sill flashings give good long term protection - but were not a requirement. The joinery flange at the sill simply overlaps the cladding sheet by 10mm and is supposed to be open to allow any moisture entering above to drain to the outside of the sheet below. These are often closed off with sealant or plaster by both professionals and home owners not realising they are inhibiting drainage.

The jambs are supposed to have either a bead of sealant between the joinery flange and cladding sheet or a closed cell foam strip. The problem with sealant is that the thermal expansion of the aluminium joinery is far higher and if not installed as a proper sealant joint (bonded to surfaces only on 2 sides) can tear on stretching leaving gaps that allow water entry. The problem with closed cell foam strips is that if they are compressed too much the cells rupture and stay closed instead of pushing outwards to maintain the seal between the two surfaces and again the resulting gaps allow water entry.

An even bigger problem is when sealant or foam strips are not installed at all then prevention of moisture is reliant on either paint and/or the texture coating adhering to the joinery which again can not match the higher thermal expansion of the aluminium and therefore fails and leaks.

It is possible that you have issues around all your exterior joinery and I suspect along with others here that a full re-clad may be necessary to repair properly and legally. If that ends up being the case don't rush to install the same cladding again but on a cavity - take your time as there are plenty of cladding options with similar installation costs that can add significant capital value thereby partially mitigating the repair cost - and of course make your house look far smarter.

Fred99

13684 posts

Uber Geek

#1087160 11-Jul-2014 13:59

The OP - Grahame - has suggested that he wishes to insulate (exterior) walls. This would require building consent (except in Chch in which case it's exempt at the moment - but still has to meet code). I doubt that it would get building consent to install insulation from the inside with direct attached cladding of that type. I assume this was planned to be done by removing internal linings - which is still quite a major job - so the ease with which insulation can be fitted as part of an exterior reclad (cost of batts etc is not very much) is further reason to do things that way.

DarthKermit

5346 posts

Uber Geek

Trusted

#1087798 12-Jul-2014 16:28

Hi OP, would you be able to post a pic of what it looks like from the outside? In particular any holes or damage that are letting water penetrate.

Whatifthespacekeyhadneverbeeninvented?

mattwnz

20149 posts

Uber Geek

#1087804 12-Jul-2014 17:02

How old is the house? These days that type of cladding would need a cavity, which creats a separation between the framing and cladding to drain . I am guessing that there is either no jamb flashings or the head flashing is leaking or not installed properly. If it is an older house the cladding maybe asbestos, so you should get it checked. Non asbestos products usually have it written on the sheeting that it doesn't contain asbestos. If it doesn't have this, then treat it as asbestos. Make sure you get a good removal company if you are removing it, one that sprays the sheets with a PVA type solution to keep the material together. It is the dust that is the main problem when removing it.
I am thinking a full reclad maybe the long term solution, and if it is asbestos, then removal costs will also be high. The window frames maybe alright, as aluminum is durable, only the reveals may need replacing, but if you are getting a full reclad, you will probably want double glazing and thermally isolated frames so you don't get condensation.
More pictures of outside and the overall building may help, as well as photos of the exterior of the windows .

grahamhowe

8 posts

Wannabe Geek

#1088237 13-Jul-2014 20:20

Hello all, Thanks for all your replies and you Gazbo. The hosue was built in 1981 and I suspect at the time it WAS to spec but now... not so. Ill make the best of it and do what I can to make it warm and dry which it currently is, it's this window that is leaking. On the outside I have sealed the window against the cladding with a sealant leaving the bottom to drain as Exceed windows advised. So that leaves in question the seals which are surprising in good nick so again my thoughts on the water damaged wood frame is because there were gaps between the frame and cladding before I sealed it, there was some give in the frame too when you pushed it so that I assume could be where blame should be pointed.

I've included further photos of the inside which show the work I'm doing to replace the damaged wood frame.

D1023319

524 posts

Ultimate Geek

ID Verified

#1088257 13-Jul-2014 21:24

Hi, i get the impression you have not taken the window out before sealing from outside.

Hence i think this will only be a temp fix as sealants dont last and sealants not only keep water out, but it keeps it in too.

If it was me,
i,d remove the window,
replace the framing below the window with one piece,
place a zinc flashing on top.
Nb the flashing should be notched into vertical framing to direct any drips coming down the side outside when it reaches the base

Without seeing outside top of window, a flashing might be suitable.

Cheers

mattwnz

20149 posts

Uber Geek

#1088263 13-Jul-2014 22:38

It is certainly a mess, but you can't see what the cause of the problem is from the outside. Photos of the outside would be needed for that. Sealent will unlike solve the problem too, if it was me I would be getting head jamb and sill flashings installed.

Wise

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Glassboy

850 posts

Ultimate Geek

ID Verified

Trusted

#1088587 14-Jul-2014 14:21

grahamhowe: Hello all, Thanks for all your replies and you Gazbo. The hosue was built in 1981 and I suspect at the time it WAS to spec but now... not so. Ill make the best of it and do what I can to make it warm and dry which it currently is, it's this window that is leaking. On the outside I have sealed the window against the cladding with a sealant leaving the bottom to drain as Exceed windows advised. So that leaves in question the seals which are surprising in good nick so again my thoughts on the water damaged wood frame is because there were gaps between the frame and cladding before I sealed it, there was some give in the frame too when you pushed it so that I assume could be where blame should be pointed.

Where you have the new wood about to go in, is there any damp proof course on top of the concrete skirt? The rot could have easily spread up, as down.

grahamhowe

8 posts

Wannabe Geek

#1088624 14-Jul-2014 14:42

Yep, I'm adding a bit of damp proofing before the new timber goes in. Will added external photos tonight.

mattwnz

20149 posts

Uber Geek

#1088663 14-Jul-2014 14:50

Glassboy:
grahamhowe: Hello all, Thanks for all your replies and you Gazbo. The hosue was built in 1981 and I suspect at the time it WAS to spec but now... not so. Ill make the best of it and do what I can to make it warm and dry which it currently is, it's this window that is leaking. On the outside I have sealed the window against the cladding with a sealant leaving the bottom to drain as Exceed windows advised. So that leaves in question the seals which are surprising in good nick so again my thoughts on the water damaged wood frame is because there were gaps between the frame and cladding before I sealed it, there was some give in the frame too when you pushed it so that I assume could be where blame should be pointed.

Where you have the new wood about to go in, is there any damp proof course on top of the concrete skirt? The rot could have easily spread up, as down.

That is true, although it would also probably show on the floor covering against the wall. Would also depend on how high the ground is against the salb footing on the outside. It also depends on how much the cladding overlaps down the side of the footing and that there is at least a 6mm gap between the footing and cladding. I would add that they need to make sure that new building wrap is installed to patch the hole. I think the job needs a building consent, especially as it may involve installing insulation to external walls.

Bung

6480 posts

Uber Geek

Subscriber

#1088687 14-Jul-2014 15:11

mattwnz: That is true, although it would also probably show on the floor covering against the wall.

Floor covering? It looks like it's a basement or a garage. Now that it's obvious that the wall isn't lined it's hardly a high risk repair. It's taken 24 years to get to this point so it's not a sudden fail pointing to design.

mattwnz

20149 posts

Uber Geek

#1088693 14-Jul-2014 15:15

Bung:
mattwnz: That is true, although it would also probably show on the floor covering against the wall.

Floor covering? It looks like it's a basement or a garage. Now that it's obvious that the wall isn't lined it's hardly a high risk repair. It's taken 24 years to get to this point so it's not a sudden fail pointing to design.

I thought they had removed the wall lining, and they did say it was their house, not that it was a garage or shed. But looking at the newest photos it does look to be an outbuilding. If it is just a shed, then the best longterm solution maybe to rebuild it. Especially if it is asbestos.

gazbo

89 posts

Master Geek

#1088798 14-Jul-2014 18:39

Just a few more points:

1. Air seals around penetrations in the cladding are the most important factor in preventing leaks. Effective continuous seals with no or minimal air leakage provide a positive pressure inside the house compared with the outside which constantly pushes against the outside air and any water travelling with it.

15mm is a bit big to seal continuously with expanding foam unless the installer has a good steady hand. Generally 7 - 12 mm works well but ensure you use a PEF backing rod so that the foam is only bonded on two sides between the joinery reveal and the trimming framing and that a width to depth ratio of around 2:1 is maintained. If in a Very High or Specific Design wind zone expanding foam may not hold up and a modified silicon sealant will work better. Just make sure whatever you use actually bonds to any wrap or tape at the perimeter of the opening. Do not use flashing tape all around the perimeter of openings, only to the four corners 150mm each way and also the entire sill - but anywhere else is simply unnecessary and expensive.

2. Replacing any wall framing affects NZBC clause B1 and therefore requires a building consent. There are valid arguments for exempting non structural framing such as nogs but studs, lintels, bottom and top plates or window trimmer replacement all push works into requiring a building consent.

3. Any works resulting from external moisture NZBC clause E2 will also require a building consent.

4. Asbestos used as wall cladding or ceiling coatings stopped being manufactured and installed in New Zealand in 1984.

My steak is ready so i'll shut up and go eat it. Hope it goes well.

Cheers,

Garrett

Fred99

13684 posts

Uber Geek

#1088840 14-Jul-2014 19:25

An aspect to building consent - if required to do whatever Grahame intends - is that changes made may not be required to bring things up to present code, but must not perform worse than what is existing.
Looking at the photos above, there's a cut off double stud under the window frame. Looks to me that perhaps it was the remains of a jamb on the side of an original window, and at some stage the window has been replaced with a larger one. Perhaps poor workmanship has caused the problems. There's also a decent crack in the foundation wall - which looks large enough to me to warrant a repair (epoxy injection).
The single 90x45 "new timber ready to be installed" isn't adequate IMO - should be double stud full length to the lintel, as it's supporting weight above. That is restricted work (LBP only) even if not needing consent - not "DIY".

mattwnz

20149 posts

Uber Geek

#1088843 14-Jul-2014 19:34

gazbo: Just a few more points:

4. Asbestos used as wall cladding or ceiling coatings stopped being manufactured and installed in New Zealand in 1984.

Cheers,

Garrett

If the house was constructed in 81, then the OP should be treating it as being asbestos. Hammering new timber near it could kickup dust, or potentially damage/crack it. I think the OP needs to get a pro in, because whatever is done is probably going to need a consent.

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