repairs needed after rainwater getting into house

we’re having a large extension done, which has involved stripping the tiles off half of the existing roof. the builders opted not to use a “tin hat” to protect the existing structure, saying the (9 year old) existing felt would keep it dry.

Unsurprisingly this has not worked out, and after heavy rain the last week, we have significant wet patches both on our upstairs ceilings (where water is dripping through the plasterboard), down the walls (where the plasterboard paper backing is peeling off in places) and on bits of carpet.

In a lot of places the plasterboards are being replaced as the building work anyway, but where this isn’t currently the case, what repairs should we be asking the builders to do, both on plasterboard and supporting woodwork. Is a skim/repaint enough? Are floorboards ok after getting soaked through for a few weeks?

Did you tell the builders as soon as it was clear the felt wasn’t keeping water out?

Are floorboards ok after getting soaked through for a few weeks?

Well they will expand, that’s for sure. Depending on how tight they were to start with and how securely fixed down they were they might pop up.

But once dry they should be fine, it won’t cause lasting damage.

the builders opted not to use a “tin hat” to protect the existing structure

They opted to save themselves a few quid 😉

Did you tell the builders as soon as it was clear the felt wasn’t keeping water out?

yes, we’ve been extremely hot on sending them pictures of every new bit of damp thats coming through. Obviously this appears to us some time after its actually rained (as it takes a while to soak through)

Well they will expand, that’s for sure. Depending on how tight they were to start with and how securely fixed down they were they might pop up.

But once dry they should be fine, it won’t cause lasting damage.

good to know. The whole house is only 9 years old so I’m kinda assuming all the 1st floor flooring is T&G of some kind, just wanted to make sure it wasn’t permanently knackered after getting wet

T&G flooring is very likely to pop up when soaked, you/they might have a problem getting it back down until it is completely dry, which might take a while. Get them to hire dehumidifiers.

Unsurprisingly this has not worked out, and after heavy rain the last week, we have significant wet patches both on our upstairs ceilings

I would say it is surprising!  It’s not necessarily the tiles/slates that keep the water out – that’s also the job for the ‘felt’.  It shouldn’t leak just because the tiles aren’t there so something may be amiss there.

 what repairs should we be asking the builders to do, both on plasterboard and supporting woodwork.

The framework will be absolutely fine.  I’d let the plasterboard dry and see what it’s like but if it’s a partition wall I’d expect it to also be fine.

I would expect the floorboards to actually be chipboard and these could have swollen so need checking out.

Dehumidifiers strategically placed until dry. Use a moisture meter to check dryness. Zinsser Coverstain or BIN to seal water stains on walls and ceilings before redecorating. Hopefully the worst you’ll get is a few cracks and stains.

The whole house is only 9 years old so I’m kinda assuming all the 1st floor flooring is T&G of some kind, just wanted to make sure it wasn’t permanently knackered after getting wet

Chipboard doesn’t like being soaked.  If it’s just a little water on the surface you should be good. If it’s had time to soak into the board then the glue will have been compromised and may need renewing.

If it’s chipboard flooring that’s got soaked and especially if it isn’t moisture resistant chipboard, I would expect it to be knackered.

If there are no tears in the felt and it hasn’t been flapping about in the wind where it has been cut for the new structure, then I expect the leaks are connected to where the felt has been pierced by the roofing batten nails.

I wouldn’t expect it to usually be much of a problem but the UK has had some very heavy rain recently. I river cascading down might cause leaks especially if the batten has pulled away and left a slight gap

As Sharkbait says, the felt should be waterproof, so maybe an issue to take up with NHBC for a 9 year old house, plasterboard replacement is simple to builders, doubt you’ll have any issues there, floorboards a little more sensitive, beams will need drying out as well if it’s soaked in there as well, lots of work if you are lifting floor boards though.

Interesting choice of words on ‘builder opted to not use a tin hat’.  I presume if you were insistant you wanted it they could/should have quoted you the price for the job with the tin hat (at a good chunk more) and without?  You are the client after all and define the spec they should be working to.

Unless the water damaged is significant, whilst being a pain in the ass, it is probably still cheaper to fix overall than to have erected a tin roof over the whole house.

thanks all

At the moment we don’t know how soaked the various bits of the house are as access is tricky (all the floorboards are under carpet which is under all our furniture at the moment) – additionally we’re a long way from everything being weathertight, so the damp is likely to get (a lot) worse before it gets better. The builders have dehumidifiers we can borrow, but doesn’t seem much point until there isn’t water coming in any more.

It seems like the water is getting through the felt at the joists (as the joists are very wet), rather than randomly dripping through – I assume this will be where the batten has been nailed through to the joist – I don’t know if this is to be expected or not. I’ll head up there in the next heavy downpour to confirm

I assume this will be where the batten has been nailed through to the joist – I don’t know if this is to be expected or not

Well I’m not particularly surprised, as I said earlier especially if there is a slight gap under the batten where it is nailed. Try to make certain that the batten is as tight against the trusses as possible.

Wet carpets sound like a nightmare! I wouldn’t take the attitude of “oh well, we will have to put up with more rain penetration until the work is finished”. Get them to resolve it now, can’t they cover it with tarpaulins? And I would get the dehumidifiers on straight away.

Btw if the rain has come from the roofing batten fixing points and it has thoroughly soaked everything I think you have been unlucky, I would expect the amount of rain to get through to be minimal. You must have had some torrential rain!

just been up to re-inspect the roof during a downpour (we had an inch last night, so a reasonable amount, but there was already some dampness coming through before then).

looking at the felt theres a few rips or almost-rips on it, which aren’t there on any of the unexposed felt – a lot of it seems to be close to where edges of wood are. My supicion is that as they stripped the roof/some of the existing batterns then had wind blowing into the void, the felt has been pushed hard against the remaining batterns due to a sail effect and caused it to rip at that point.

Interesting choice of words on ‘builder opted to not use a tin hat’. I presume if you were insistant you wanted it they could/should have quoted you the price for the job with the tin hat (at a good chunk more) and without? You are the client after all and define the spec they should be working to.

Unless the water damaged is significant, whilst being a pain in the ass, it is probably still cheaper to fix overall than to have erected a tin roof over the whole house.

we didn’t insist – we asked whether the scaffoding was going to encompass a roof, and they said no it wasn’t needed as we already had felt (and it seems from this thread like that was a reasonable approach to take). I work in IT so didn’t ask for them to change it. At this point, its likely not much slower to get the place tiled than it is to get some scaffs in to put a hat on it all anyway – the tilers were meant to start today (2 faces are ready to go for them).

Get them to resolve it now, can’t they cover it with tarpaulins? And I would get the dehumidifiers on straight away.

We’ve certainly asked them to do that, but given where we’ve got to at this point, we’re also pessimistic about what the outcomes are likely to be.

It is normal to not need a tin roof if the felt is in decent condition, or if its replaced – my neighbour is having a lot of work done and their roof is currently just felt and battons

The use of ‘the builder opted’ makes it sound like it was their choice.  In fact its yours, they recommended you didn’t need it, and you agreed.

I also work in IT btw, if your spending many thousands with builders its worth spending some time swatting up otherwise you are going to get a few more of these problems and it could lead to some trouble (speaks from experience after ‘trusting’ a plumber knew the best way to do something rather than explicitly telling them exactly what needed to be done and where the pipes and outlets needed to be….)

I do some work with scaffolders and can tell you that to cover the roof would cost a fair number of £1000’s.

You may not have gone for it even if given the option (which maybe you were) as it’s a big chunk of money and taking a risk on the weather may have seemed worth it.

TBF to the builders they could have quite reasonably assumed that the  ‘felt’ would/should have been fine.

My supicion is that as they stripped the roof/some of the existing batterns then had wind blowing into the void, the felt has been pushed hard against the remaining batterns due to a sail effect and caused it to rip at that point.

Sounds very plausible imo.

TBF to the builders they could have quite reasonably assumed that the ‘felt’ would/should have been fine.

Well it was only nine years old. Although they should have been extra careful of the result of removing battens and releasing felt to the mercy of the wind, it was always likely to cause it to rip or tear, see above.

When we had a reroof the roofer told us the membrane was waterproof.  I would be concerned yours leaks and you are about to retile.  Before we had the roof done I was always up there with buckets to catch drips.  Problem was the wind, it blew the rain along and upwards.  Patching the membrane was unsuccessful, I tried loads of times.

We paid extra for some membrane roofer recommended, it worked and well worth it.