Slate Roof With No Underfelt - A Problem??

If a terraced house had a slate roof with no underfelt, would this be something that most people would want fixed immediately i.e. taking off all the slates, and installing underfelt and replacing all the slates again.

Or is having no underfelt on a roof not a major problem, and something which can be lived with i.e. not usually considered an "urgent" problem.

Reply to
SuzySue
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In my experience, this is perfectly usual in older houses and doesn't constitute a problem at all.

Nick

Reply to
nick nelson

Our roof (1930s) isn't felted. It's not a problem except where there are gaps in the slates. When we replace the roof (probably this year) we will felt it.

Reply to
Grunff

It is certainly not unusual to get roofs like this, especially in the North. The consensus seems to be that the lack of weatherproofness is offset by the excellent ventilation (which quickly dries out any water or snow that does blow in)! The roof space will also be pretty dirty.

I would say that if the roof looks in good condition (i.e. no broken or displaced slates, no rotten or broken timbers) then this is not a major problem. If you do need it doing, it is not normally hugely expensive (maybe a couple of thousand pounds?). tony

Reply to
Tony

It's very common indeed in older properties and is not a problem in itself. Having felt provides a second line of defence in case a slips out of place. Not having it means that you need to be a bit more vigilant with keeping an eye on the roof from the outside and the inside, since a slipped slate may mean water starting to come in. Even then, if it is only one slate, the overlapping of the slates would mean that that is not usually a major issue for a few days until it can be fixed.

If the roof is in generally good condition, then it is reasonable to leave it alone. On the other hand if the slates appear crumbly at the edges or if you experience a lot of them slipping because the nails have rusted, then it can make sense to have the roof relaid. This involves taking the lot off, and the battens and then laying felt, battens, probably re-using some slates and replacing others with second hand good slates.

I would see what happens over the course of a year or so and then decide. Obviously if there are any signs of water coming in or slipped slates, these should be fixed.

.andy

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Reply to
Andy Hall

No. It's something you would address if you needed to refit the slates for some other reason though.

Houses designed and built that way have survived hundreds of years, so of itself, it can't be considered "urgent". Repairing a leaking roof would be urgent though, e.g. if an unlined roof has misaligned or missing slates.

Reply to
Andrew Gabriel

If the slates are in good condition and well fixed then it's not a problem at all. Once a slate slips though it needs to be attended to with rather more urgency than on a roof with sarking.

Without sarking the roof space will probably be dirtier as windblown atmospheric fallout (dust) will find it's way in. Stored items will need dust sheets over them.

Reply to
Dave Liquorice

Hi Susan: neither, it can be lived with indefinately. All original Victorian slate roofs are feltless.

There are 2 minor caveats with unfelted roofs:

  1. Theyre almost always very old and the occasional slate will probably drop off and need refixing. Budget maybe £30 a year.
  2. They let water wind and dust in, the wind dries out the water no problem. It just means you cant use wind blocking insulation up against the woodwork, as it would trap water.

If youre buying one, look at the slates, replace any broken ones, refit fallen ones. And if the roof has more than about 25% of slates fixed with visible metal tabs its time to consider reroofing.

There are lots of unfelted roofs still working without any problem.

Regards, NT

Reply to
N. Thornton

Not a problem and anyway the slates have a much longer life than felt which was installed in the past. My slate roof has wooden sarking. When I installed some Velux windows I found the sarking was in perfect condition after 100 years. One problem you may come across is that surveyors will report seeing daylight. Possibly a true report but worthless without qualification which it never is. Its the through ventilation which keeps the roof timbers dry something some BCOs fail to recognise also when insisiting on roof vents.

Alan

Reply to
Alan James

Actaually the felt does eff all. Its there to stop the slates being blown off.

It does make the rough moree draughty even than a building inspectors mandatory eaves vents though, so you might rather want to insulate counter batten, insulate and board out the loft for snugness...

MUCVH better bang for your buck than re-felting.

Of couse, if the roof ever needs redoing in toto, by all menas felt it. Its not expensive.

Reply to
The Natural Philosopher

Out of curiosity, from what year/decade was underfelt commonly used underneath roof slates?

Reply to
SuzySue

I would have said it was about the vintage as cavity walls so increasingly from 1915 to universally by 1940.

Reply to
Ed Sirett

Thanks very much guys for all above info. Much appreciated!

Reply to
SuzySue

Hopefully with a breathable membrane and not 'felt' (old-fashioned?)

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Reply to
Andrew

Well it's not been urgent all these years has it?!

Providing the roof is intact and straight consider a foam type under tile job. That will insulate and hold everything in place BUT is a bitch if you ever do need to remove a slate cos it effectively glues them all together.

Reply to
PJO

Our new (to us, built 1880) house doesn't have felt, and others in the same street have had problems after felting theirs due to lack of ventilation to the roof members. one thing about not having felt is there's plenty of space for air to get in and dry things out. If the house was built without one, just keep an eye out for missing tiles in high winds. If it originally had one though, I'd be inclined to get it re-felted pretty quickly.

Reply to
L Reid

Dont even think about it.

Regards, NT

Reply to
N. Thornton

Why not?

I used it on a property and not only did it save me a load of time and money it also saved the roof!

Reply to
PJO

For a short time, possibly. But removing ventilation from the rafters etc will almost certainly cause long term problems. It also prevents easy inspection for leaks.

Reply to
Dave Plowman

Well you quote one reason yourself, when (not if) the roof needs repairing it won't be a straight forward job and you won't be able to reuse any of the slates.

The of course when (not if) water does penetrate the slates it can't dry out quickly and thus increases the chances that the rafters and/or laths are going to rot.

In the short term, yes. But when the roof finally fails it will be a much bigger and longer job thus more expensive.

Reply to
Dave Liquorice

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