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1. JonEdwards - Member

   This is a bit long - sorry!

   We've just moved into a new house - 1920s ish stone clad semi detatched. 3 cellars (one of which will be the bike hole) and 3 attic rooms in the roof.

   The cellars are reasonably dry (a pair of dehumidifiers have made a big difference though, but are vented to the outside world by airbricks at the front, and a back door with a 1" gap at the bottom. I presume having some airflow is a good thing, so I don't want to seal it all up, especially as it's never going to get really warm down there.

   The ground floor is suspended wood boards which currently have foil backed bubblewrap stapled to the underneath. Is it worth filling the gaps between the joists with insulation material hung in netting tacked to the joists? Also the central heating pipework is run in 10mm microbore pipe with no insulation. The ususal DIY suspects don't stock 10mm insulation, but I've found it in a few specialist suppliers, but it's bloody expensive compared to 15mm. Any advantage to using the right stuff or will 15mm be fine?

   Up in the roof:- The rooms are built into the eaves and all have sloping panels, there's then storage cavities around the walls at floor level, plus a small loft right up in the peak of the roof. Everywhere has been floored out (T&G chipboard). The eaves are vented to the outside, and there's a good old draught...

   The loft has sheets of 50mm polystyrene as insulation under the floor boards. Is this any good? I'm assuming not?

   The storage areas are completely uninsulated.

   I can do thick insulation in the loft easily enough (will have to remove and raise the chipboard), plus rafter depth stuff in the storage areas and the backs of the vertical walls of the rooms (mostly plasterboard on studs). I'll need to put

   What I don't know how to do is deal with the angled sections where the plasterboard is fixed directly to the rafters - there's a 6" deep gap, that's it. Can't see me getting anything down there. Also don't want to compromise the ventilation...

   Lastly the house is cavity wall construction
   Pros and con's of cavity wall insulation...? I hear it can cause damp problems by bridging the two walls? The quick peek down it I had suggest that there's a lot of sh!t down there already, mind...

   Thanks for reading. Advise away please!

   Cheers,

   Jon

   Posted 7 months ago #
2. don simon - Member

   Have a read of this.
   http://www.energysavingtrust.org.uk/In-your-home/Roofs-floors-walls-and-windows/Cavity-wall-insulation
   And don't forget the windows.

   Posted 7 months ago #
3. JonEdwards - Member

   Thanks for that.

   Quite a few of the windows are double glazed already. The rest will get done as soon as I have some cash free again!

   Posted 7 months ago #
4. Drac - Moderator

   Lots of grants available for cavity wall installation, had mine done the other week for £99 and it's made a huge difference.

   Posted 7 months ago #
5. wisepranker - Member

   Lots of grants available for cavity wall installation, had mine done the other week for £99 and it's made a huge difference.

   Same here, we had our walls done last year December and the difference was noticeable straight away, well worth the £120 or so that it cost.

   Posted 7 months ago #
6. midlifecrashes - Member

   I have a big 1901 Victorian/Edwardian semi with solid walls, rooms into the pitch of the roof (no loft) and cellars under the front half. The coldest room was always the dining room, in the back corner that got no sun but has a bay and two other windows. When we redecorated that room last year I lifted a couple of floorboards and stapled Space Blanket (Rockwool in a shiny condom) between the joists. It's made quite a difference to the room, and only cost a few quid by buying the subsidised gear. We also use the highest TOG rated underlay under the carpets and caulk up the floorboard to skirting gaps before laying. Never going to be cheap to heat, but a lot better than it was and more comfortable.

   On the top floor, have done half so far, putting 100mm of Kingspan under the existing roof, and 50mm on the outside walls, re-plasterboard and skim. Made a big difference. Still have two rooms up there to do. Don't want to go that far on ground floor as we'd obliterate period features etc.

   As for the cavity, I have never had a problem with damp or bridging problems in other houses.

   In your loft, you could insulate the pitch of the roof rather than the floor to create a warm roof. Use whatever suits your budget, but some loft conversions use Triso10 to get good U values without bulk.

   Posted 7 months ago #
7. stucol - Member

   Interested to note on the Energy Savings Trust site says NOT to use cavity wall insulation if the wall is subject to driving rain.

   Personally my main walls (mid terrace) are parallel to the prevailing wind. Next door, both sides, have had CWI done but i am waiting a couple of years to see how they get on dampness wise. We do live high up and in an exposed area.

   Other local friends have had it done but the severe winters over the last two years make it difficult to judge any savings. It is very cheap to have installed though.

   JonEdwards, if you cant get 10mm internal diameter pipe insulation cheap, you could just buy the 15mm and trim it lengthwise. Tiewraps will close the gap or contact adhesive ? Realistically it's not going to be much of a problem to just use the 15mm as is. Especially if you insulate the cavity/joist gap it's in anyway.

   Posted 7 months ago #
8. JonEdwards - Member

   Thanks for all the advice guys.

   As far as the cavity walls go - one is pretty sheltered (and has the least number of windows/most wall, so presumably is the one to get done first and see what happens. The front face of the house is directly into the wind, so is getting a battering at the mo, but also is mostly bay windows and the door, so not that much actual wall. Also the whole place is stone clad, so I'm not sure how water permeable (compared to brick) it is anyway.

   The cavities are currently open at the top. Do you need to close them off before filling them? Or is that somthing the CWI firm just deal with?

   Cheers!

   Posted 7 months ago #
9. don simon - Member

   If the bay window faces into the wind, perhaps this would be a good read to. Page 13 gives a few comparisons and the related u values.
   http://www.historic-scotland.gov.uk/thermal-windows.pdf

   Posted 7 months ago #
10. slowoldgit - Member

    If you've got dehumidifiers running in the cellars, you don't want much ventilation thru the winter - one or the other. A one-inch gap under a door sounds a lot.

    Posted 7 months ago #

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