Re-Roofing or Not?

[malcolm]

I'm planning to get some people in to do the exterior of my house next year. I want to get scaffolding up, fix the roof and guttering, remove the paint from the exterior, and fix the external wood frame and windows.

For the roof we have small plain tiles at the front and slate at the rear (the pitches are different). I think it was put on in 1910 - there is no vapour membrane or eaves or ridge ventilation.

The small plain tiles on the front roof are missing many of their fixings and they are slipping. There are leaks where tiles or batons are missing, and around the leading (or possibly cement work) on the high part of one of the chimneys. I think the tiles need to be lifted, batons replaced, badly fitted skylight fixed, tiles re-fixed, and flashing sorted on chimneys. Here is a picture.

I had been thinking about a vapour permeable membrane just for the sake of catching any wind blown drips, and that would require eaves ventilation.

The slate roof at the rear isn't causing any problems at the moment. The surveyor mentioned some of the tiles had started to de-laminate, and some have been replaced to the right of the photo below hung on metal clips. Here is a photo:

We spoke to the roofer about lifting and replacing the slates when we were up there and getting the whole house fitted with a membrane. He said half the slates would be broken, new ones wouldn't match, and we would be better off fitting new. I think this is where most of the cost in his whopping 20K quote is.

I'm leaning towards getting only the plain tiles at the front lifted and replaced, fit a membrane and eaves ventilation at the front. Leave the slates at the rear for a few years until they start to cause trouble, and use the ventilation from lack of vapour barrier at the rear as an alternative to ridge ventilation.

I've not checked whether building regs actually require a membrane. Thinking about it there is no need to really have one. 100 years after being botched into place the roof still works, and leaks on the ceilings do encourage timely repairs.

Does that sound sensible or would you do something different? We'll get some more quotes too.

 

[plasticpigeon]

It seems a bit pessimistic to assume 50% broken slates. Scaffolding is expensive so it seems sensible to do both sides of the roof to me if possible.

 

[stuart45]

Roofers don't like reusing the slates. It means that they can't charge you for new ones, and take the old ones away to reuse on another roof.

 

[plasticpigeon]

I didn't want to say that Stuart, but I suspected that was the case.

 

[Zebra]

Plus it's easier to work with all new stuff - we prefer to run new cables rather than test, check and reconnect the old, but will do what the customer wants.
I'm not clear from your quote whether you're going to replace the clay tiles on the front, or refit the existing. Did the roofer have any similar pessimistic outlook on how many of those might be reusable?
I'm also unclear what you mean by " use the ventilation from lack of vapour barrier at the rear as an alternative to ridge ventilation."
Do check up on Building Regulations though. I might well be wrong about this but I seem to recall reading that not only do you need a membrane if you are having an entire roof replaced, you also need to have insulation over the rafters.

 

[plasticpigeon]

Insulation over the rafters isn't needed unless it will be a living space. However loft insulation will need to be brought up to current regs if the roof is recovered as it will be classed as a new thermal element. I can't imagine anyone not insulating their loft though!!!

 

[a twig]

I might well be wrong about this but I seem to recall reading that not only do you need a membrane if you are having an entire roof replaced, you also need to have insulation over the rafters.

Only if you tell someone that you are having your whole roof replaced.... :twisted: :twisted:

 

[MatthewC]

You want to find a roofer who will use reclaimed slates on the back. You don't really want new slates on an old building, and you certainly shouldn't mix old and new as the new will always stand out. I was told to expect 30% wastage on the old ones which was about right for my roof, but your roof looks better than mine was! Find a supplier of old slates, either a reclamation yard or even a specialist supplier like http://www.oxfordsalvage.co.uk. Reclaimed are much cheaper (sorry, "less expensive") than new, and look better.

Yes, BRs say you need inspection if you are "replacing a thermal element" which you are as soon as you lift the covering and replace battens. I didn't ask BC to inspect as the roof was my first application for LBC and it never occurred to me that Planning and Building Control didn't talk to each other!

Matthew

 

[malcolm]

I need to update the roof insulation anyway. When you have a change of use the whole house is classed as a new thermal element. I'll check the membrane with building regs - you are probably right.

The plan is to re-use the clay tiles at the front. Quite a few have spalled due to moss and would be replaced by reclaimed tiles. I assumed the 50% slate loss at the rear is because the slates are nailed on and likely to break when removed. The rear is not really visible from anywhere so it wouldn't matter visually if there were a mix of new and old slates, though reclaimed is worth looking at.

I'll get some more quotes in and make a decision. I'm not sure the rear really needs doing, though work now would prolong it's life past a point where I would be bothered about it any more.

 

[CliffordPope]

So you are not intending to take the opportunity to match front and back? To my mind the tiles look nicer on that house.

If you had new (reclaimed?) tiles on the back, but only "repairs" on the front, that wouldn't be a whole new roof so no problems with regulations?
Then you could negotiate with the roofer to sell him the reclaimable old slates, or get the scaffolding up and remove them yourself?

 

[Flyfisher]

Yes, BRs say you need inspection if you are "replacing a thermal element" which you are as soon as you lift the covering and replace battens. I didn't ask BC to inspect as the roof was my first application for LBC and it never occurred to me that Planning and Building Control didn't talk to each other!

Is it really "replacing a thermal element" when you re-tile a roof? I'd suggest that in the vast majority of houses, it's the insulation laid between and over the ceiling joists that forms the "thermal element" and the role of the roof is to keep everything dry, not necessarily warm.

If the attic space is used as a room then it's clearly a different case.

 

[kreyszig]

50% breakage on slates doesn't seem crazy to me. Our slates aren't in great condition so we were told about the same. Having said that, I've pulled a few slates myself recently and haven't broken a single one! .. maybe 50% IS a bit on the high side!

Enlarged nail holes can be re-drilled too. We've changed roofers now but both of them automatically used reclaimed slates.
Are you sure you need new battens? If you don't have any rot you may be able to get away with internal insulation, repairing the tiles that have moved, and re-flashing the chimneys.
A good portion of that 20k will be the labour to remove and re-lay the tiles and slates, I would surmise. I had a similar quote to do our roof, not sure on the size relative to yours, but that included a couple of long valleys being redone and flashing around a chimney. I think labour was over half.

 

[skier-hughes]

50% breakage on slates doesn't seem crazy to me. Our slates aren't in great condition so we were told about the same. Having said that, I've pulled a few slates myself recently and haven't broken a single one! .. maybe 50% IS a bit on the high side!

I expect you took care and they will work with some care but mainly speed. You would need to work out if it is cheaper to have them working slower and retaining more tiles or wasting tiles but with half the labour cost!!

 

[kreyszig]

That's a good point!