Rendering timber frame

[Dsmart]

drawing for my timber frame 1st floor extension specify 18mm exterior ply, breathable membrane ( roofing felt or similar I assume), EML and 20mm 2 coat render finish. I'm concerned about the render adhering to the membrane, is this an issue? Would rib lathe make any difference over standard s/s EML sheets?

 

[pinenot]

It's been my experience that building paper was the normal choice in these situations, but whoever detailed the drawing would be the best person to ask...pinenot

 

[dann09]

As above, 15 lbs black roofing felt will work fine over the ply sheathing.

Render will "stick", but sort out with the renderer what materials, esp. the finish, he/she is going to use.

I've, typically used "chickenwire", but that was in a warmer climate. Talk to the applicator.

 

[limerockconstruction]

Hi Mate - last time I built a timber framed extension by hand it included counter battening to form a cavity - your spec doesn't mention this....

I would go

stud
18mm WBP
Tyvek (or other if you wish)
counter batten
building paper
EML
render finish

The building paper is only behind the EML to allow the spread to get his first coat on. It then binds to the EML and building paper becomes irrelevant! But I think the counter batten forming the cavity is pretty important.....the only thing i'd add is make sure you get your abutment detailing right - your timber frame will move at a largely differing rate to the existing building.

 

[Deluks]

What he said, but be sure to use some sort of plastic drainage strip at the bottom of the cavity over windows and doors.

 

[noseall]

We doubled up on the eml and it gave a better key, the last time i had to do it.

Which was...er....aboot 20 years ago.