Cavity Wall Insulation in mid-terraced house

Possom

If getting cavity wall insulation injected into the walls of a mid-terraced house, are the beads injected into the front and back walls only?

Or are the beads also injected into the two internal side dividing walls?

ariba10

I doubt that there will be cavity walls between terraced houses?

When were they built?

daveyjp

Just the front and back. If the property has a large proportion of the walls taken by windows and doors it isn't worth doing the work.

Possom

Okay, thanks guys.

27col

There is no need for a cavity wall unless the wall is exposed to wind and rain. Hence there is very unlikely to be a cavity wall between two adjoining properties. It would normally be a 9" solid brick wall. The houses either side are in effect providing the insulation.

Furts

27col wrote: »

There is no need for a cavity wall unless the wall is exposed to wind and rain. Hence there is very unlikely to be a cavity wall between two adjoining properties. It would normally be a 9" solid brick wall. The houses either side are in effect providing the insulation.

On terrace, or semi, houses built in recent decades it has been the norm to build cavity walls between the houses. Sometimes when getting to the roof space this wall was built as solid to save time and materials.To determine the construction one should look in the roofspace.

Any prudent person would request, or stipulate, that the party wall be insulated. Check the position with neighbours regarding The Party Wall Act - though I cannot think of logical reasons for objection.

In general, I would foresee the cavity wall insulation being done with a lance.

Extract_insulation

In recent months there has been media coverage about problems with cavity wall insulation. I would not recommend any party wall being insulated unless you 100% it free from debris, from my experience removing cavity wall insulation on the outer walls is bad enough. Just make sure they put cavity barriers/brushes in between you and your neighbours. On a mid terrace there should be 2 on the front & 2 on the back unless your neighbours have been insulated.

Furts

Extract_insulation wrote: »

In recent months there has been media coverage about problems with cavity wall insulation. I would not recommend any party wall being insulated unless you 100% it free from debris, from my experience removing cavity wall insulation on the outer walls is bad enough. Just make sure they put cavity barriers/brushes in between you and your neighbours. On a mid terrace there should be 2 on the front & 2 on the back unless your neighbours have been insulated.

The gist of this is correct IMHO.

But on balance I disagree with the overall picture. For CWI to be extracted means wet is the issue. On party walls wet should not be an issue because these are dry walls. Hence they should be OK and not need extracting - assuming the installation was correct.

Conversely, if a home owner is getting CWI installed it would be foolish to ignore the party walls in a terraced home. These are the less risky walls for future problems.

Extract_insulation

A lot would also depend on the product used. You may still get voids in bead insulation, although less likely than fibre. Beads do get caught up in cob webs leaving veins of voids which brings there own issues. Also one bead supplier (I won't name) is getting a reputation for not bonding properly with the PVA glue they use. Also who owns the gap?

[Deleted User]

If the two properties are kept at the same temperature, then nobody will gain from the insulation. If the temperatures are different, then one householder will lose as much as the other gains. In reality, nobody is going to have a neighbour who keeps his house cold enough to make the insulation worthwhile.

Furts

jack_pott wrote: »

If the two properties are kept at the same temperature, then nobody will gain from the insulation. If the temperatures are different, then one householder will lose as much as the other gains. In reality, nobody is going to have a neighbour who keeps his house cold enough to make the insulation worthwhile.

The cold neighbour situation does occur. Elderley people who will heat only one room and then perhaps to a temp of 16 degrees, empty neighbouring properties where the owner is deceased and the home will eventually be sold, BLT properties during void periods...

Add to this that party walls were traditionally built in concrete block even if the external walls were aircrete. This certainly occured for at least 30 years. These party walls are far less efficient at conserving energy. This is then compounded by the floor joists bearing into these walls, surrounded by cracks and voids for heat to escape. By todays building standards this is all poor practice, but then it was the norm.