Sat, 23 May 2026 07:10:03 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224771#Comment_224771 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224771#Comment_224771 Fri, 22 May 2015 14:31:40 +0100 a63245347
I have a flat roofed conservatory lean-to extension. The wall that was the old external house wall is now the internal conservatory wall.

I've discovered that there is no insulation in the cavity in this wall. The rest of the house has had CWI.

So that means that the heat from the conservatory and the room on the other side of the wall is going into the cavity and up into the cold loft.

I can get to the cavity from the top by sliding up the roof tiles and getting underneath the felt.

I have had the following suggested to me

1. "closing the cavity at the top of the wall" using expanding foam so that any heat doesnt rise straight into the loft
2. "pouring" cavity insulation beads down from the top.
3. blowing beads in using a vacumn cleaner blowing into a bag of beads and a spare hose on the other side of the bag into the cavity. I already have 2 big bags of fire retardent beads.

The cavity is 50 to 60mm deep. The wall is about 7m long and single storey. I suspect it is too small for a commercial firm to be interested.

Any thoughts on how best to treat this would be much appreciated. Thank you.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224772#Comment_224772 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224772#Comment_224772 Fri, 22 May 2015 14:35:30 +0100 gravelld
My current plan is to do either 2 or 3, wait a few weeks for settlement, then do 1. I'll probably start with 2 to see how easy/fast it is and if it takes too long, 3.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224777#Comment_224777 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224777#Comment_224777 Fri, 22 May 2015 16:44:23 +0100 tony
Edited: gears should say beads. Sorry]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224781#Comment_224781 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224781#Comment_224781 Fri, 22 May 2015 17:22:22 +0100 gravelld https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224784#Comment_224784 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224784#Comment_224784 Fri, 22 May 2015 18:42:20 +0100 a63245347
Good point Tony about revisting and topping up the insulation after settling.

I was thinking of using a normal 1/2" garden hose pipe rather than a vacumn cleaner hose on the bag outlet for a bit more control and because the cavity is quite narrow.

There are a couple of cables in the cavity that I need to remove 1st to prevent reaction.

Is there any practical DIY way of adding glue somehow so that if the wall is drilled in the future the beads stay in it?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224785#Comment_224785 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224785#Comment_224785 Fri, 22 May 2015 18:46:02 +0100 skyewright Posted By: a63245347
3. blowing beads in using a vacumn cleaner blowing into a bag of beads and a spare hose on the other side of the bag into the cavity.
I think the usual arrangement is to have a "T" pipe, with the down stroke into the bag. Air is then blown into one end of the top piece, beads get sucked up by the venturi effect & air plus beads emerge from (a flexible pipe) attached to the other end of the top piece.

Happy to be corrected...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224786#Comment_224786 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=224786#Comment_224786 Fri, 22 May 2015 18:49:49 +0100 barney
Ditto if you have to drill the wall later - drill a small hole and then spray in some diluted unibond or similar PVA - then you can drill a larger hole without ending up ankle deep in polybead

Regards

Barney]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225025#Comment_225025 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225025#Comment_225025 Thu, 28 May 2015 21:22:07 +0100 cjard https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225027#Comment_225027 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225027#Comment_225027 Thu, 28 May 2015 21:32:23 +0100 skyewright Posted By: cjardSky right, that's the way my sand blaster works.. But then again the warmcel blower machine I saw on YouTube didn't seem to work that way.. Looked more gravity fed.
Many years ago (25?) and in a different place we had warmcell loft insulation installed & yes I think they fed the blower machine via a funnel like hopper? However, my comments above were about the polystyrene beads the OP intends to use, quite a different material to handle?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225440#Comment_225440 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225440#Comment_225440 Sat, 06 Jun 2015 10:43:56 +0100 a63245347
Plan is

1. Tip polystyrene beads in the cavity (I'll leave the cables there for now - they'll be disconnected during redecoration in the next few weeks)
2. Seal the top with expanding foam

The next step is replacing the felt-on-ply with a warm flat roof.

I'm planning the make-up as follows from bottom to top, after removing the existing felt.

Existing Ply decking
Self adhesive vapour barrier
140mm non foil insulation boards
EPDM cover

Here's a pic of what I think I need to do where the new raised insulated roof joins onto the pitched roof.

Remove fascia
New vapour barrier over decking which extends to the right hand side to cover outer leaf of bricks
Cut the insulation boards in between the pitched rafters and extend the boards all the way to the thermalite inner leaf. This will cover over the bead filled cavity
Screw 18mm OSB lay board over pitched rafters, onto the tile battens. Board to extend onto insulation to provide a surface for the EPDM to stick to
EPDM over the top
Tiles back on

Does this sound reasonable?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225441#Comment_225441 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225441#Comment_225441 Sat, 06 Jun 2015 10:44:33 +0100 a63245347 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225443#Comment_225443 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225443#Comment_225443 Sat, 06 Jun 2015 11:38:14 +0100 woodgnome https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225459#Comment_225459 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225459#Comment_225459 Sat, 06 Jun 2015 21:16:08 +0100 chuckey Frank]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225460#Comment_225460 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225460#Comment_225460 Sat, 06 Jun 2015 21:57:00 +0100 a63245347
thanks for all the comments. Next stop tomorrow is felt roof off, and hopefully vapour barrier down.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225474#Comment_225474 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225474#Comment_225474 Sun, 07 Jun 2015 09:31:40 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225495#Comment_225495 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225495#Comment_225495 Sun, 07 Jun 2015 19:34:12 +0100 gravelld
Any thoughts on the amount of glue mixture Tony, given the volume of bead?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225500#Comment_225500 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225500#Comment_225500 Sun, 07 Jun 2015 21:15:08 +0100 tony forgot to say earlier]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225517#Comment_225517 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225517#Comment_225517 Mon, 08 Jun 2015 09:10:42 +0100 andyman99 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225520#Comment_225520 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225520#Comment_225520 Mon, 08 Jun 2015 10:11:42 +0100 gravelld https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225526#Comment_225526 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13384&Focus=225526#Comment_225526 Mon, 08 Jun 2015 14:45:24 +0100 AMG