SBMS Posted July 18 Share Posted July 18 We are looking at propassiv as the internal substrate for our vaulted roof makeup. Blown in cellulose. Has anyone got a specific detailing for where the propassiv board meets the wall plate at the eaves. If the board is tight up against the inner leaf/wall plate it seems there’s going to be a tapered gap - is it best to foam this and then tape over? Anyone got any photos if they’ve done similar? Link to comment Share on other sites More sharing options...
MikeSharp01 Posted July 18 Share Posted July 18 If I have this right - the wall plate supports joists etc, you just need to tape the sheets, wall / roof, together before fitting the wall plate. Don't forget that blown cellulose is pretty air tight when pumped at high enough density - the sort of density you need if you want to avoid slumping. 1 Link to comment Share on other sites More sharing options...
Iceverge Posted July 18 Share Posted July 18 3 hours ago, SBMS said: We are looking at propassiv as the internal substrate for our vaulted roof makeup. Blown in cellulose. Has anyone got a specific detailing for where the propassiv board meets the wall plate at the eaves. If the board is tight up against the inner leaf/wall plate it seems there’s going to be a tapered gap - is it best to foam this and then tape over? Anyone got any photos if they’ve done similar? If you're going to spend the cash on a boarded product I'd prefer to put a layer of OSB sarking on instead (rodent protection) and an airtight membrane inside. You could verify that you certainly have a full fill of cellulose then. Link to comment Share on other sites More sharing options...
SBMS Posted July 18 Author Share Posted July 18 5 minutes ago, Iceverge said: If you're going to spend the cash on a boarded product I'd prefer to put a layer of OSB sarking on instead (rodent protection) and an airtight membrane inside. You could verify that you certainly have a full fill of cellulose then. We are planning on a steico wood fibre board on exterior and passivplus interior serving as the vapour and airtightness barrier. Just wondering how we detail the junction of the board at the wall plate Link to comment Share on other sites More sharing options...
Iceverge Posted July 18 Share Posted July 18 (edited) Just butr as far down the ceiling as is practical and use a strip of membrane to join to the walls should do I would have thought. Edited July 18 by Iceverge Link to comment Share on other sites More sharing options...
Russell griffiths Posted July 18 Share Posted July 18 Before you fit the board, run a fat bead of some sort of air tight caulk along it, then tape over the join afterwards. belt and braces. 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted July 18 Share Posted July 18 4 hours ago, Iceverge said: If you're going to spend the cash on a boarded product I'd prefer to put a layer of OSB sarking on instead (rodent protection) and an airtight membrane inside. You could verify that you certainly have a full fill of cellulose then. That is how ours is done. Link to comment Share on other sites More sharing options...
SBMS Posted July 18 Author Share Posted July 18 3 hours ago, MikeSharp01 said: That is how ours is done. What airtight membrane did you use? Did it withstand the pressure of the cellulose pumped in? Link to comment Share on other sites More sharing options...
MikeSharp01 Posted July 18 Share Posted July 18 We used intello plus as it has strengthening strands for exactly that - but it didn't work as expected we had bulging much more than expected on the first pumping. We put additional supporting vertical battens under the horizontal battens that hold the plasterboard, at 300mm centers to keep it in check. (Main studs are 600mm. This bulging gets worse when it gets really warm as the plastic stretches and we got some slumping on the tall.columns. So I let it slump and them filled any gaps with more cellulose when I found the voids with an IR camera / strong torch- if you put a bright LED against the membrane you can see holes. Attached is a pick of a roof section the 300 centers. 1 Link to comment Share on other sites More sharing options...
SBMS Posted July 19 Author Share Posted July 19 17 hours ago, MikeSharp01 said: We used intello plus as it has strengthening strands for exactly that - but it didn't work as expected we had bulging much more than expected on the first pumping. We put additional supporting vertical battens under the horizontal battens that hold the plasterboard, at 300mm centers to keep it in check. (Main studs are 600mm. This bulging gets worse when it gets really warm as the plastic stretches and we got some slumping on the tall.columns. So I let it slump and them filled any gaps with more cellulose when I found the voids with an IR camera / strong torch- if you put a bright LED against the membrane you can see holes. Attached is a pick of a roof section the 300 centers. Did you blow the cellulose in yourself or get an installer to do it? Worrying there was voids that you discovered if using an installer? Link to comment Share on other sites More sharing options...
MikeSharp01 Posted July 19 Share Posted July 19 3 hours ago, SBMS said: Did you blow the cellulose in yourself or get an installer to do it? Worrying there was voids that you discovered if using an installer? Yes we did blow it in ourselves and there were not any voids when we did it for 8 months, then we had heat wave and I noticed the bulges getting worse and found the voids at the top. So we added the intermediate battens - chamfered the edges to avoid damage the membrane and then refilled the voids. No problems since. 1 1 Link to comment Share on other sites More sharing options...
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