Slate Roof

[WaveyDave]

Hi

Hope some of you knowledgable guys can answer my question!

I'm buying a property that has a slate roof. It's a 1930s semi, with original slates. Surveyor has said roof is coming to end of life. Builder I spoke to says that he'd just strip the slates, felt underneath (no felt at the mo), and re-fix slates.

Most things I've read about slate roofs failing suggest corrosion of the nails/fixings. Does slate wear, or is it generally down to the fixings? I've heard of de-laminating, how does this show up?

Cheers

Dave

 

[JohnD]

Not a bad idea if the slates are still in good condition. If he's a local builder and familiar with roofs like yours (ask to visit some other houses he's re-roofed and speak to the owners) he should have a good idea of the best way.

You can expect to have some damaged slates replaced with new. Ask for the new ones to be put at the back of the house where they won't show (they will not match visually).

If your house was built for slates, do not put concrete tiles up. Apart from looking vile they will be too heavy for the timbers.

BTW see if you can have a modern dry-verge fitted (I have slates with a mortar edge, and it falls out ) see //www.diynot.com/forums/viewtopic.php?t=83375&start=0 (it looks like I will be stuck until/unless I have a lot of tiles taken off).
The felting will make your loft very much cleaner.

Round here (coastal environment) they only use stainless nails or bronze fixings on roofs, these do not go rusty and seem to me to be worth having for the modest extra cost.

 

[Nige F]

get a good leadworker to make a verge cover without removing the tiles delamination .......they tend to go soft and flakey on the weathered surface ..........less likely with best quality Welsh ones ,look you

 

[WaveyDave]

Don't know if they are welsh, but as I am in Wales, perhaps I'm in luck ;0

 

[Softus]

If slates get wet and aren't properly ventilated, then they can delaminate and/or go squidgy.

 

[WaveyDave]

OK

So other than delamination and nail/fixing corrosion, why might a surveyor say that a roof needs replacing?

 

[Softus]

...why might a surveyor say that a roof needs replacing?

Roof, or just the roof covering?

Have you asked the surveyor who made the statement?

 

[daverik]

If your house was built for slates, do not put concrete tiles up. Apart from looking vile they will be too heavy for the timbers.

Not always the case. It is wise to check the load capacity of the timbers, but usually it will be ok. Sometimes cost is a priority and the cost of tiles is a quarter of slate.

We work on 40% breakages and then adjust the price accordingly. Check the roofer has made allowances for unseen damaged slate beforehand, then there wont be any nasty suprises in store.

 

[WaveyDave]

...why might a surveyor say that a roof needs replacing?

Roof, or just the roof covering?

Have you asked the surveyor who made the statement?

I don't have the report with me, but from what I can recall it says something along the lines of -

the roof is starting to show its age. A visual inspection of the loft from the loft hatch doesn't identify any problems. It is expected that repair requirements will increase on a year on year basis, hence you should budget for a new roof.

I've paraphrased, but IIRC that's pretty much it. The mortgage surveyor said the roof covering needs replacing now, and suggested a retention on the mortgage. They both mentioned that if I went for tiles, then I'd need a suitably experienced person to confirm the roof structure would take the additional weight.

I had a roof coveing replacement quote for a previous house I was going to buy (almost identical, but slightly smaller) which came in at £4000+VAT

As its a slate roof, I'd never consider anything else as it would be out of character. Roof did offer manufactured slate look-a-likes which he said were cheaper but not as good.

I'd resigned myself to getting it done, but having researched it, I couldn't understand why the slates need to be changed, they don't seem to have changed colour or anything.

 

[Softus]

I think you're being mildly naive.

The whole business of mortgaging, as with any money-lending activity, is about risk reduction. Identify the risk, estimate the probability, quantify the impact, and make some contingency plans.

The lender is interested only in getting its money back. The surveyor is interested only in earning a living and not getting sued.

Therefore, if the roof is old, any surveyor will, without much thought, indicate that it will "deteriorate further over time", and recommend that you plan to replace it. My cat could be as accurate as that.

If the lender wants to place a retention on it, so be it. It will be cheaper for you to not do the work immediately, since you'll have a smaller mortgage.

If you buy the house, then leave the roof alone, wait until the summer, then have someone you trust (or that has been recommended to you as trustworthy) examine the roof and report on their findings, and then decide.

 

[WaveyDave]

I think you're being mildly naive.

The whole business of mortgaging, as with any money-lending activity, is about risk reduction. Identify the risk, estimate the probability, quantify the impact, and make some contingency plans.

The lender is interested only in getting its money back. The surveyor is interested only in earning a living and not getting sued.

Therefore, if the roof is old, any surveyor will, without much thought, indicate that it will "deteriorate further over time", and recommend that you plan to replace it. My cat could be as accurate as that.

If the lender wants to place a retention on it, so be it. It will be cheaper for you to not do the work immediately, since you'll have a smaller mortgage.

If you buy the house, then leave the roof alone, wait until the summer, then have someone you trust (or that has been recommended to you as trustworthy) examine the roof and report on their findings, and then decide.

Thanks softus. You've been very helpful.

The lender didn't actually put a retention, although it was recommended. My surveyor did say that the roof *may* last for up to 10 years. However, as there's not felt beneath the tiles I'm worried about water damage in the event of losing tiles. I don't know how much cheaper it might be to lift the slates, felt and then replace them with new nails. He also mentioned the cast iron drainage starting to rust, and suggested it might be a good time to change them when we do the roof.

I am trying to work out all the things that need doing. I only have a finite pot of cash, and its available now, so if something needs doing, I don't want to end up spending the cash and then find out after!

 

[Softus]

I understand WaveyDave - working out where the money gets spent is always tricky.

Something else that's tricky is predicting how many slates will be reusable, because only when you take them off can you then see the unventilated/rotten areas.

Get yourself a good roofer to advise you further, but £4000+VAT seems a bit steep (no pun intended) to me.

If you have a street-facing part of the roof, and a rear-facing part, then one option is to budget for being able to re-use half of the slates, placing them on the front, and replacing all of the rear ones, i.e. where it's not very visible, with artificial slate.

 

[WaveyDave]

Tell me about it Softus!

Most difficult thing is getting trades to quote, as we don't own the house yet its impossible getting access for them!

Will have to wait until we've completed, it's just that we're trying to get as much done beforehand as possible.

 

[Softus]

Most difficult thing is getting trades to quote...

Standing on the other side of that particular fence, I have to confess to you that I never quote. I have too much work and not enough time.

You do have my sympathy though. What I recommend is that you build up a small selection of tradespeople who are good, and whom you trust to do the work without overcharging. You might be surprised how many of us trade on goodwill and word of mouth recommendation, and who would be mortified if anyone thought they had overcharged.