Cavity Insulation in old tenament building?

[Samuel]

Hi All,

I own a 100 year old tenement building in Glasgow. It's a ground floor flat and my heating bills are extortionate. I plan to fix this along with various other energy efficiency changes before the winter sets in.

The flat was treated for damp/rot approximately 10 years ago. There is some sort of paint or sealant on some of the inner walls along with a row of small ventilation holes at ground level across the whole of the back exterior wall. I'm concerned that reducing the ventilation would cause damp or rot to build up.

Is it possible to cavity-fill these flats and is it wise?

Thanks in advance!!

Sam.

[meow2222]

People dont learn.

you shouldnt reduce ventilation when insulating. Check any vents stay clear, as cwi has been known to block them.

if cavity walls, and the cavity is big enough, yes.

depends on the cavity. If its smooth sided ie brick or block, then sure. If its rubble built or ratbond, no.

NT

[Phil Anthropist]

The cavity wall insulation 'surveyor' will assess the suitability of your property. In my case he drilled holes and inspected the cavities using a fibre-optic instrument.

[robgraham]

If it is a typical stone built flat in Scotland then I would expect that the walls will be efectively a double skin of stone with all the rubble thrown loose in the middle - hence there isn't a real cavity, certainly not one that can be filled as effectively it is filled already.

I would look to your windows - draught proofing, etc as your 'roof' insulation will be near enough perfect with presumably 3 flats above you. The other heat loss area would be the floor.

Rob

[Lobster]

Are you sure these holes are for ventilation? Sound just like the holes drilled for the purpose of injecting damp-proofing fluid.

Does the paperwork for your damp/rot treatment say that a DPC was injected?

David

[Stuart]

The holes are to insert damp treatment fluid not for ventilation . cwi.????? wgat's that .

Stuart

[Stuart]

That's EXACTLY what these holes will be .If you look at other flats near you will almost certainly see similar holes .There should aslo be a metal grating which is an air vent to the solum of the building and this should not be covered up nor filled in . As for the "cavity" walls if it is a traditional tenEment then there will not be a cavity as such . Tenement walls are pretty thick as these flats were traditionally made of sandstone blocks. I would suggest that you check the flooring for gaps and also the skirting and the window frames etc .

Stuart

[Owain]

More likely they're little ceramic "ventilators" plugged into the wall to create a pseudo-DPC.

Owain

[Owain]

Agreed. However in a 100 year old tenement there are quite likely lath and plaster internal walls spaced away from the outer stone. Especially where the L&P is continued across a chimney breast there could be over

1' of gap. This gap should not be filled, but it is often possible to remove the L&P and replace with an insulation+plasterboard composite.

Major job though, and may result in loss of cornice.

If access can be gained to the solum then it is often possible to put insulating batts between the joists under the floorboards. Again, not a small job depending on access.

Owain

[Stuart]

My experience of where I stay in a similar aged building is that the ceilings are L+P and also the areas on either side of the windows where the walls are angled away from the outer walls .Otherwise the walls are plastered brick .As I have found out removing the L+P is a very messy business.

Stuart

[Phil L]

If there's a cavity there then it can have CWI, but *only* if the rest of the block has it too...one flat in a block cannot be insulated unless they're ring beamed which it almost certainly isn't.

[Dave Fawthrop]

|Samuel wrote: |> Hi All, |>

|>

|> I own a 100 year old tenement building in Glasgow. It's a ground |> floor flat and my heating bills are extortionate. I plan to fix this |> along with various other energy efficiency changes before the winter |> sets in. |> The flat was treated for damp/rot approximately 10 years ago. There |> is some sort of paint or sealant on some of the inner walls along |> with a row of small ventilation holes at ground level across the |> whole of the back exterior wall. I'm concerned that reducing the |> ventilation would cause damp or rot to build up. |>

|> Is it possible to cavity-fill these flats and is it wise? | |If there's a cavity there then it can have CWI, but *only* if the rest of |the block has it too...one flat in a block cannot be insulated unless |they're ring beamed which it almost certainly isn't.

It is a *ground floor* flat, so the insulation can not fall down to the flat below. They still do foam don't they? that stays within a meter or so of the hole.

[Phil L]

There's not many companies who use foam anymore and fibreglass can't be used, not because it will fall down the cavity, but because any moisture which comes down the cavity from above sits on top of the insulation whre it stops and causes (severe) damp, no insulation firm will look at a job like this because they can't garuantee it.

[Stuart]

As explained elsewhere the OP's flat is a tenement property typically built of red or grey sandstone and there is no "cavity" as such because of the method of construction .

Stuart

[Phil L]

We don't know beyond doubt that there is no cavity, hence my proviso, 'If there's a cavity there then it can have CWI..' Which is a moot point anyway, because it can't.

[robgraham]

Ah yes - forgot that one about the L & P. Moved into this Scottish farm cottage in the 70's and went to fit shelves for books only to get all the plaster dust in my eyes from the draught running up the back. Excellent under floor ventilation had been introduced when the wooden floor and L&P were fitted probably in the late 20's, but the house insulation went effectively to zero.

As the property was having a major make-over, I did remove all the L & P (by the way if you are doing this watch out for the plaster 'hooks' through the laths as they will fall down as you attack the wall and will bridge the gap to the solum - nasty experience of reversing that!)

- and I did go the 2 " rockwool insulation route in the gap behind the plasterboard. Plasterboard, polythene sheet membrane, 2" rock wool and the 3 ft of sandstone/rubble/sandstone. That was 20 years ago and it has worked perfectly. 1300l of oil does me for the year.

There is no moisture through the wall from the outside due to the rubble in the middle and the membrane on the inside stops moist air condensing in the insulation.

Rob

[Owain]

I remember one house where the wind would come whistling out of the earth hole in the electric sockets.

Owain