Posted By Dilettante on 17 Nov 2018 12:38 AM

Posted By scottishjohn on 16 Nov 2018 10:59 AM
Is that really a good idea onto OSB you maybe sealing moisture in -breathable is surely the way ?

There are vapor open fluid-applied and P&S systems out there.

actually the air passing thru is what rotted the OSB as it condensed on the underside of the OSB roof deck, so sealing it is what you would want to do at the interior skin , if you contain the air, then you can control how it exits the building thru an HRV system.
in tight buildings the control of moist air flowing from inside to outside in cold climates and outside to inside in hot humid climates is vital to maintain healthy indoor air quality

I can find NO sips maker suggesting stick on membrane for roofs --all use top spec breathable +double battons +some even what another membrane under tiles as well

no planning authority would pass use of OSB sip for basement even with stick on membrane +drainage system etc

our planning are very cautious --even with concrete basements some planning dept want external and internal drainage systems+sump for periodic inspections

the one company that does uses MGO/cement boards sips ,says yes with membrane for basement+ drainage --but no mortgage company or insurance company will accept it.

think we must have significantly damper climate than US

Posted By scottishjohn on 17 Nov 2018 09:57 AM
I can find NO sips maker suggesting stick on membrane for roofs --all use top spec breathable +double battons +some even what another membrane under tiles as well

no planning authority would pass use of OSB sip for basement even with stick on membrane +drainage system etc

our planning are very cautious --even with concrete basements some planning dept want external and internal drainage systems+sump for periodic inspections

the one company that does uses MGO/cement boards sips ,says yes with membrane for basement+ drainage --but no mortgage company or insurance company will accept it.

think we must have significantly damper climate than US

Permatherm SIPs approve membrane and direct applications of, shingles, Metal or barrel tile.

Planning authorities in UK or US do not make material use determinations , that is the duties of the Building Officials ..... planning and building departments carry out separate and distinct functions

I would not use MGO board above or below grade, it is known to absorb water/ moisture and is banned for use in shower areas by the International Residential Code

Damp in US, guess you've never been to our Pacific Northwest in Winter

I just cant stress enough to people the dangers of using Mgo board anywhere moisture is present , I have seen these problems first hand ...
this link is a great report outlining what I have been preaching for years :

http://www.bunchbyg.dk/wp-content/uploads/2016/08/MSSCE2016_Word_208.pdf

this JUNK! it absorbs moisture , it leaches chloride and is corrosive to metal,
I predict you will soon start hearing more about Mgo falling off it has been attached with screws/nails or if any cladding has been attached to Mgo it will start to separate
I feel sorry for people that got sucked into using this stuff
Chinese drywall 2.0

"Damp in US, guess you've never been to our Pacific Northwest in Winter"

I,m talking about most of the year LOL