bump .....

PVA?

Posted By: an02ewi dont think i would just trust to an adhesive. but would also use some machanical fixings? all adhesives would probably require a clean dry substrate, can you really provide that with osb timber frame outside on a building site?

... well the OSB has been stored dry from delivery, and covered in DPM once up ...

The guy who's turning up to apply the render is suggesting "maite" ... the same stuff he's putting on the outside to bed mesh into before applying the top coat/s of render (which I think must be the PAREX system)

I've asked about mechanical fixings but no one seems to use these except for fixing to masonary ...

Posted By: DarylP.... try sprayable adhesive....? 5/25 litre tins, sprayable via a pressure pot, or maybe thinned down via a gravity spray gun....

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Hi Daryl, I've been really careful to get a flat surface so shouldn't need any extra thickness to take account of bowing etc, so spraying would be fine. A quiet bit of trowel & roller is more my style though!

I guess I'll defer to the renderer's experience?

I've recently used "Soudatherm Roof 250" PU spray foam to attach PIR to OSB3 on a flat roof - it seemed pretty good. Their site has a nice test result sheet for EPS to OSB3 bonding. Third of a ton uplift strength per square meter under their test conditions (have a dig around for the PDF). You'll need some mechanical fixing - at least until it's set to ensure good contact.

Cheers,

Tim.

Thanks for the Soudatherm tip, Tim - very timely, and Parex and Souda are talking to OK it. Think we'll use it anyway on current job, vertical as well as slope.

Has another great advantage - 0.036 lamda, so unlike normal EPS/EWI adhesive, can happily enter the joints between the boards - in fact the edges can be glued 'as you go' rather than retro-filled with squirty foam after the adhesive has set.

The Soudatherm will prob also serve as the 'bubble-glue' we're already using to glue n screw the 9 OSB to the stud frame.

In all, ano2ew of this forum, as builder, thinks this de-specialisation allows him to board-fix as part of his work, only employing EWI-specialist plasterers for the render finish. So great - thanks.

Posted By: fostertomThanks for the Soudatherm tip, Tim - very timely

Glad it was of use...

Some usage tips based on our experience:

If applying at temperatures sub 10 degrees, then best to keep the tins warm (e.g. bucket of warm water - as it happened, they fitted quite nicely in our kettle - warmed to ~30 degrees) - Soudal said they're fine down to 5 degrees, but didn't really seem to work very well below 10 in our experience. The cans cool somewhat during prolonged usage due to de-pressurisation, so best to pre-heat.

As with most expanding foams, cold or insufficiently shaken tins (shake every minute or so during use) will result in you running out of propellant before the tin is empty.

If the board or substrate are at all non-flat, then you'll need to ballast reasonably heavily or clamp with sufficient pressure to keep the materials in good contact for about an hour - if you don't do that, but instead apply pressure for too-short a period (e.g. Soudal's recommended period for normal flat boards), then you end up with little stringy towers of hardened glue holding the board and substrate apart (viewed from the side - imagine looking into a dense pink forest) - resulting in an uneven surface and a (relatively) weak bond. Mechanically fixing with sufficient density (temporarily or permanently) would also solve the problem, as would using smaller boards I think.

Hi Timsmall, could you email me? ta!

an03ew promises to write the full guide to this question - got it working well.

Hi an02ew, reading this with interest! Do they use that adhesive to make SIPS panels do you think? have you tested the structural strength? I'm interested in this to create more attic space in roofs and as a base for the full Solar Roof we're working on.

It would be interesting to see the pictures. JPG format works for me.

David

Go on andy - you've plenty to say about that, then i'll chip in

Stuck for time again, so just a quicky

I did manage to get hold of two cans of the soudatherm 250 (roof fix) free as a trial, and after talks with Soudal the manufacturers was informed, there is in early production a revised versions for wall fixing? The 250 product stuck very well and i can imagine that for roof fixing when gravity would hold in place untill the adhesive cured it works well, however for us wall fixing, the product needed holding in place untill it cured or a series of planks and block to sucure untill cured.

The DM EASY product as a contact adhesive and once stuck is cured. however if Soudal can delevope the new wall fix product and address the curing time they will get my vote.

Will try to post pics of passive insulated formwork for my foundations that i made using DMEasy and 2 layers of 150 EPS tommorrow.

NickinKernowAbout 15.5 kW/m^2.

Are you sure you don't mean 15.5 kWh/m^2?

Nice test ST, what adhesive was used? what was the application? what is the curing time?

Posted By: an02ewsorry for crop on pic cant seem to get anything larger than 500kb uploaded any suggestions

email them to yourself first, make a GBF file to save them and post the pictures from the GBF file.