Cavity Wall Insulation

[stoofur]

I am the freeholder of a block of two flats. I live in the ground floor flat and our leaseholder lives in the first floor flat. Our maintenance agreement is as required. i.e. if something needs to be done I get it done and the leaseholder pays half.

I am quite interested in getting cavity wall insulation but my leaseholder does not want to. As she says it causes damp.

So I have three questions:-

1, Does cavity wall insulation cause damp?

2, If I do decide to get the cavity wall insulation done. Does the leaseholder have to pay half?

3, If we get it done and it does cause damp can she sue me?

Our flat is pretty cold and our heating bill is pretty high so I am interested in your opinions.

Thanks

[buildersmate]

Q1: Not as far as I know. It doesn't cause damp but it may contribute to an already poor situation. Before an installer installs, he used to have to undertake a simple survey to assess (amongst other things) the exposure factor of each external wall. A westerly-facing wall in an exposed and windy location might not pass. The reason for this is that CWI prevents air circulating in the cavity, and in some cases can assist the water in the outer leaf to transfer across the cavity ties into the inner leaf. This happens if the metal cavity ties do not have the mortar removed that drops down onto them during construction (it should be removed by the brickie as it happens). The way I have seen as then cause a problem is by a damp patch about a foot in diameter in very wet weather showing on the inside centred around the offending tie.
Suggest you seek advice from your proposed installer.
Q2: No, it is surely a capital improvement, not maintenance. Would you expect the leaseholder to fund double-glazed windows? However, in view of the cost-savings to the leaseholder you might be able to negotiate a contribution.
Q3: No. Though ask the installer about what it would do in the unlikely event of damp penetration - it should be part of their warranty.

[stoofur]

Thank you for your answer. With regards to answer two. The leaseholder has a 157 years remaining on her lease. So surely if it increases the value of the flat then it is for her benefit also?

[buildersmate]

I suppose that it true - I hadn't thought of that.
Not sure if you have a legal or a moral case (or both).

[buildersmate]

Here's another thought if she is bent on being pig-headed about it.
See whether it is OK to install up to the line of the first-floor only. Small holes are drilled in the outer leaf and the foam injected - it travels about one metre in circumference from the hole, which is then refilled with mortar. Trouble is the cost of installation won't be much difference from doing the whole house.

[stoofur]

Thanks Buildersmate. That is a good idea. I'll look into that.

[flyciderman]

There are new rules about service charges be very carefull