Hi chaps can anyone tell me please what the spec on a bay window ply ?the job is basecoat then topcoat mono.do I use the big roll of fibre tape over ply instead of elm? Many thanks time to be sensible nick.
I rung Weber about this problem and their answer is basically it can't be done in their Weber Pral.m . The material is brittle and will crack with any movement which you will most likely get on a timber bay. This particular job was a typical 3 bed semi with double bay. There is the Webertherm Xl or XM material which is for insulation but will most likely be a different shade in colour to the Pral.m. There is also their polymer top scrape which might do the job but again may be a different shade and a different texture. so in this case none was acceptable. Their only suggestion which was off the record was to ply, breathable felt, expanded metal lathing, scratch coat of pral.m, let it stiffen up and then bed mesh into it and a second coat of pral.m making sure that both meshes and felt wrapped round onto the brickwork. But warn the customer that it may still crack if there is the slightest movement which is nothing new with Weber Mono anyway:RpS_scared:. Sorry for talking Weber talk but apart from some Primo I have only used Weber Monocouche.
It has given me more than my fair share of problems lately. One job I have done to their specs, it cracked between the window sill corner and a down pipe bracket 900mm away at the usual 45degrees to the window and because the mono is touching the sill at the end I am to blame. No sign of a slight crack between the plastic and mono when the supposed expanded sill shrunk back and we cut round the sill when wet but it slumped back.
You would think the tech rep would have supported me with being a regular buyer instead of this feeble get out excuse. Now rend aid is fully meshed with the mesh going upright, horizontal, 45 degrees and again in the mono with definite gaps between the mono and any frames, then fill the gaps in with silicone sealant so it makes no difference at all as silicons sealant is god at stretching but crap at compacting. Lets see what Kevin Grainger can blame me on next time Ivory Pral.M cracks.
Any ideas what Weber could come up with next anybody?
they look for any reason to pass the buck the rats, i leave a gap as i been caught with that one before. the reps usualy no f all, im sure it was webber that a rep told us to put retarder in the basecoat to be sure of suction and it just messed it right up. thankfully its faided away up hear its just mainly krend and powerwall now
The tech guys at Weber HQ was supportive except they expect mesh to be embedded anywhere where there is going to be screws and plugs driven into the render. Thats ok if you know where someone is going to drive a screw in but it's going a bit far if you ask me. All meshed now from now on but thats only in the rend aid. Plus the usual stress patches in the mono.
It's pot luck with timber up to brick. I use ply, breathable felt with eml wrapped round onto the brick. Never had a crack to my knowledge except on two done donkeys years ago where they had, had the old bay windows took out and replaced. The cracks was hairline down the timber/brick joint. Hardly surprising bearing in mind the disturbance caused by taking old windows out. Customers actually never complained and accepted the cause. wrapping the felt round onto the brick would stop any damp penetration. But timber being flexible I always explain the risks which would help if there is a comeback. With Monocouche though this stuff is so brittle and flat any crack would stand out.