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Cavity wall insulation partly missing


j_s

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Further to my post about flue blocks and lack of insulation in the cavity Ive spoken to a couple of companies about spraying in eps beads. Not having any luck with finding someone to do it one wanted £450 which is rediculous for 5m x 1m section. 

 

Any ideas of a DIY fix for this or a company in the east Midlands? Builder said about what pouring some loose eps beads and using an electricians pull rod to push the beads down. He would also drill holes in the mortar to see if they were filling properly.

 

Any thoughts?

 

Thanks 

James

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I have self poured before, works fine. Send it in with a 5:1 water:PVA mix. But what about under windows? You could calculate the volume with the depth of the cavity and then you'll know how well it's filling.

 

JJ Crump (Sheffield based) did an install for me here in Leicestershire, but maybe for a wall of this size they wouldn't be interested...

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No windows in the unfilled part , they are either side and have insulation batts around them albeit not well fitted but me and the builder will fix that.

 

The pva mix, should it be poured alternately with the beads. Just trying to visualise the process

 

Many thanks 

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Yes, alternating is probably the best way, but it's always going to be a bit... kludgey.

 

You could also premix the bead with the solution before pouring - not tried that before, might make it slower.

 

Where is this wall sorry - what is underneath the uninsulated part, i.e. where will the beads go.

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Another way to bond beads is using a garden pressure sprayer filled with diluted PVA.  Just pour the beads in and spray the diluted PVA as you go.  The PVA only needs to be thin, as the bond only has to be good enough to stop the beads flowing out of any holes that may be drilled later.

 

I had a good look at the unit that was used to blow bonded EPS beads into the cavity walls of our old house, and it was nothing very clever.  Just a centrifugal fan blower that pushed the beads from a hopper down a pipe that was around 25mm bore, with a nozzle on the end of the pipe that had the diluted PVA feed going to it from a separate smaller pipe, fed by a small pump.  The beads are barely wet with PVA when they come out, but it's enough to hold them together when the PVA has dried out.

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Thanks guys

 

This is part of a wall from eaves to cavity tray at the bottom that needs filling

 

Will take some photos when I'm back home on Tuesday. Currently insulating at the top of the wall where the outer brick stops and the inner aerated blocks continue to the wall plate. Not insulated up to 4 courses lower than the outer brick and I can touch the coving in the bedrooms all around the whole house. Massive air leaks and no insulation from wall plate back into loft. We are changing the fascias and soffits and it's turned into a massive job with what we have uncovered :(

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But I would say - you're at an ideal time to do it when working from the outside on the eaves. Much more pleasant to do the job (in fact it's impossible really from inside because you don't have the crawl space to ensure good air tightness).

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Frantic foaming and sealants (ct1 and sticks like ****) on the out side of the blockwork and on the wall plate and plasterboard etc done. 150mm dritherm 32 plugging the missing  top of the cavity and up to the wall plate and slightly above all pinned tightly with wall tiles so they are not going anywhere and then I'll be adding the insulation batts to cover top of wall plate and back in. Will then add the missing eaves trays. Will be putting in cellulose later on too and mvhr is half in. 

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Did you consider air tightness tape? I worry about foam and sealants not lasting very long, especially with the odd mouse about.

 

I think I would air seal the cavity as well but maybe there's a reason you can't do that. Are you in an exposed place?

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I didn't consider tape up there to be honest as wasn't sure what to use but still have time. Any advice as to what tape to use?

 

Do you mean tape the inner edge of the wall plate over to the plasterboard and any where the top of the studwork is visible?

 

Thanks

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  • 1 month later...

Update to this. Got some tape and taped over the foam and still to do further in to the loft but the wall plate area was all done and insulation wraps round from cavity to over wall plate ready for cellulose.

 

Vermiculite poured into flue blocks, dry therm insulation added at the top first few meters. Will be adding continuous internal insulation from lounge up to bedroom and plugging the gaps around the joists that we will no doubt uncover when the ceiling is removed in the lounge. I had the ir camera out last winter and saw a big blue area where the floor joists are located. Will get a pic or 2 when we so that.

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