externally cladding a house with OSB??

martco

(I'm keeping an eye on some of the builds and refurbs going on in my area

especially interested in external insulation and methods etc. (not in the game just interested)

one that made me sit up and wonder recently...these fellas sheeting the entire externals of a typical 50's house with what seems to be 18"osb??

like I know osb quite well and I'd be fairly aware of it in normal use situations...so I'm watching this with wonder thinking wtf are they up to?

next thing I see slabs of external insulation going up and AHA! now I kinda see what's afoot. but at same time I've not see this before. I did my own 18 years back but the slabs of insulation went straight on block during the build (still works great no issues btw)

is this some new clever way? or not?

hydrus21

If they are mechanical fixing OSB to the exterior wall and then mechanical fixing the slab to the OSB then i dont see any cost saving between

using OSB or bonding the slab directly to the wall.

In any case, the dew point wants to be well away from the OSB.

IMO

Mellor

What was the finish if the house prior? It pebbledash it would be quite uneven. Could be to provide a level substrate

listermint

https://www.boards.ie/discussion/2058321955/externally-cladding-a-house-with-osb

It's most likely not OSB. But more than likely Steico or steico like product which is a wood derived insulation product.

I used it when I tore out my aluminium porch and replaced with a framed walled porch.

martco

https://www.boards.ie/discussion/comment/121357029#Comment_121357029

nah I'm 200% definite it was OSB not Steico, it was OSB3 to be precise

now the gaff is pebbledashed alrite so maybe that's the ultimate reasoning tho sounds expensive the price of stuff at moment jasus. would the walls be that uneven? I'm wondering too about an airgap there tho maybe that's a good thing (I'm thinking about how the insulation would be sitting atop the dash and there would be a few mm of a breather gap therefore all over)

but I would have thought risky letting OSB sit near potential moisture for prolonged period like lifetime of a gaff? like I've seen myself it does stand up well for brief exposure to wet but...maybe you could seal any cut edges I suppose, dunno

just never seen anything like it just an unusual thing to do

MicktheMan

Ewi on osb on pebbledash makes zero sense to me

listermint

https://www.boards.ie/discussion/comment/121359490#Comment_121359490

None of this makes sense tbh. None.

Unless someone hasn't a clue what they are doing. Which could be the case.

sydthebeat

https://www.boards.ie/discussion/comment/121359505#Comment_121359505

agreed...

Mellor

https://www.boards.ie/discussion/comment/121359490#Comment_121359490

Figured there would be pebbledash. The air gap, or series of air gaps, are detrimental to the performance of the insulation. Known as thermal looping or thermal bypass. Insulation works best with direct contact.

https://www.boards.ie/discussion/comment/121359505#Comment_121359505

Just insulation on OSB on pebbledash, completely agree. Thermal Loop still exists. Gap needs to be filled.

There would have to be a major mitigating factor to no simply just base coat it. I hope not simply a special on expanding foam

Calahonda52

OP: first post

with what seems to be 18"osb??

Post 5

nah I'm 200% definite it was OSB not Steico, it was OSB3 to be precise

which raises the question why the need for the first post

martco

https://www.boards.ie/discussion/comment/121361853#Comment_121361853

LOL because it was just such a surprise to see what I was seeing in such an application I suppose :)

(but thanks for your in-depth analysis of my posting there, how did I score? does my explanation satisfy your line of enquiry? ffs)