Got a small job on for a builder he has stapled breathable felt to the ply on 2 gable ends an 3 dormas as it was all set up for cladding but has since changed his mind and has asked me to fix ss mesh over this and then scratch an top, its been 5 or 6 years since done similar to this an when doing this in past its always been building paper then mesh.. I can't see breathable mesh being very breathable stapled flat an meshed over then rendered over will this felt cause problems in the future being used this way or is this now common practice, many thanks in advance...
Renderd dormas...
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johniosaif
Private Member
You need battens to create an air gap under the mesh,otherwise it may fail
Runswithscissors
Private Member
Hi Mate
As Asif (above) has said, if you are going to do it on paper and EML, you need it battened away from the ply
The modern way is to have the sheathing (your case the ply) with the breather membrane applied (as you explain), then fix 50x25mm battens vertically to match the TF studs behind, then apply a cement render carrier (something like Knauf Aquapanel Exterior) to these battens - with a gap top and bottom for ventilation.
Then apply a 5mm modern basecoat and mesh, let this dry, and then apply your finish.
Makes for a stronger and less likely to crack application, in a location that is difficult to get to if needing later repair
If you want more info, have a look at the link in my signature below, or click my forum name (top left) and go to view profile to find my contact details
Good Luck!
As Asif (above) has said, if you are going to do it on paper and EML, you need it battened away from the ply
The modern way is to have the sheathing (your case the ply) with the breather membrane applied (as you explain), then fix 50x25mm battens vertically to match the TF studs behind, then apply a cement render carrier (something like Knauf Aquapanel Exterior) to these battens - with a gap top and bottom for ventilation.
Then apply a 5mm modern basecoat and mesh, let this dry, and then apply your finish.
Makes for a stronger and less likely to crack application, in a location that is difficult to get to if needing later repair
If you want more info, have a look at the link in my signature below, or click my forum name (top left) and go to view profile to find my contact details
Good Luck!
johniosaif
Private Member
Just a quick q re the battening away from the ply.i did also most a year in Canada rendering timber framed houses . And they never battened any thing. Just paper and mesh. Now are they doing it wrong or are our regs different. They was a decent firm very sought after in Vancouver and surrounding areas. Cantex exteriors check out their website some nice work
plasterjfe
Private Member
Hi Lee
I do believe it was failures and case studies conducted in Canada that led to the whole vented cavity insuarnce clause debacle in the first place. @Runswithscissors might be able to confirm or quash that but that is what I was told from a reputable manufacturer that operate over in the states and canada
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Runswithscissors
Private Member
Wiganlad
The reason we have drained and ventilated facades in the UK is driven by the insurance companies (NHBC, LABC, Premier Guarantee, etc..). As insurance companies, they want to limit their risk and try to standardise construction methods - a drained and ventilated facade does this....
Not sure about Canada and USA, I believe they do have both ventilated and non-ventilated walling, but usually their homes, and the cladding on them, are not expected to last 60+ years, as UK mortgate suppliers demand.
Houses in Sweden 15 - 20 years ago (and some other Scandinavian countries) were built of timber frame and non-ventilated walls. After 5-10 years, walls that were on the cold side of the build started to get mould and the timber studs rotted as the moiture, in the frame when built, could not get out. This is what the UK insurance companies are afraid of!
Non-ventilated facades do get built, but the wall has to be very well designed and engineered. In the UK, house build construction is very much about price (not that spreads moan much about prices - lol), so these high performance build types are few and far between - but they do exist and Knauf Aquapanel Exterior is a product used....
In warmer countries (Southern Europe, the Middle East for example), they do not have such problems and do build non-ventilated walls.
Feel free to contact me if you want more info
The reason we have drained and ventilated facades in the UK is driven by the insurance companies (NHBC, LABC, Premier Guarantee, etc..). As insurance companies, they want to limit their risk and try to standardise construction methods - a drained and ventilated facade does this....
Not sure about Canada and USA, I believe they do have both ventilated and non-ventilated walling, but usually their homes, and the cladding on them, are not expected to last 60+ years, as UK mortgate suppliers demand.
Houses in Sweden 15 - 20 years ago (and some other Scandinavian countries) were built of timber frame and non-ventilated walls. After 5-10 years, walls that were on the cold side of the build started to get mould and the timber studs rotted as the moiture, in the frame when built, could not get out. This is what the UK insurance companies are afraid of!
Non-ventilated facades do get built, but the wall has to be very well designed and engineered. In the UK, house build construction is very much about price (not that spreads moan much about prices - lol), so these high performance build types are few and far between - but they do exist and Knauf Aquapanel Exterior is a product used....
In warmer countries (Southern Europe, the Middle East for example), they do not have such problems and do build non-ventilated walls.
Feel free to contact me if you want more info
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johniosaif
Private Member
Same as..
Runswithscissors
Private Member
Still gets built as you have been asked.
Think building regs would ask for a cavity as John stated earlier.... but get your builder to qualify with the local building constrol guy (if they are involved...?) or get builder to put what they ask you to do in writing, then if there are problems, you have built as instructed.
Think building regs would ask for a cavity as John stated earlier.... but get your builder to qualify with the local building constrol guy (if they are involved...?) or get builder to put what they ask you to do in writing, then if there are problems, you have built as instructed.
plasterjfe
Private Member
That clears that up.
What we do is we always advise on the vented cavity unless already in the spec.
We never install with a direct fix to the substrate using either insulation or boards without raising the subject with the contractor or developer in charge. They should make the call not you.
In most cases its just people not having the knowledge on the regs or wanting to save a few quid.
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