Replacement roof on stone outbuilding

[madachab]

Hi

My mother in law has recently been diagnosed with a terminal illness and we are trying to find her somewhere to live within a few miles of our house near Pickering in North Yorkshire. This is not proving very successful so far, so we are thinking about plan B.

We have an old stone outbuilding that we want to convert into an office. We were putting this on a back foot until we 'got round to it'!! But we are thinking that if we free up our second bedroom mum in law can stay with us.

Anyway, the outbuilding, although it looks a little shabby at the moment, is fairly solid and just needs some pointing and a couple of replacement stones - which I have done succesfully elsewhere on the house.

My problem is the roof. I have spoken to a few people locally and all the recommended roofers are flat out at the moment and have long waiting lists. As you can appreciate, time is not something we have in abundance, so I am more than happy to do this myself (with a few family members to help - hopefully). I am a very competent diyer, but have not tackled a roof before.

So, is this something that I should tackle or not? Any help or advice be greatly appreciated here.

Thanks in advance

 

[TexMex]

I love it. The character just oozes out all over. Is it listed?

Have you considered getting an architect to design a new roof (hopefully keeping those beams exposed). He may not charge as much as you think.

You could probably re-use those tiles as well. Once you have a design, you'll have a better idea of wether you feel up to it.

 

[masona]

Might be a idea if you can still get the tiles before you start incase of broken one, may have to go for reclaims tiles depending how old they are.

 

[madachab]

Thanks for the replies.

I didn't think about an architect, but, luckily, a local man has recently taken on a not disimalar project - his was a brick barn, so it had straight lines to lay a roof onto

He has run through a few things with me, like treating good timbers and replacing bad etc. Also not trying too hard to try and correct the sagging in the middle of the roof (is this good advice?) He was unable to recommend a particular felt to use, as his barn is still used as a barn, so he has just used whatever was cheapest! Any ideas on felt?

Having spoken to this local guy, and laid out a basic plan of action, I am happy to tackle this with a collection of friends and family to help.

We are fortunate that the timbers inside are mainly sound, although the woodworm has sought into a couple of the purlins quite dramatically

The tiles are also in fairly good nick - I don't know how long they have actually been there, but the barn was constructed at the same time as the house - over 200 years ago!!

Thanks for your help

 

[TexMex]

It's very difficult to advise on this project due to the individuality of it's design and limited information available at this end.

How much of the original roof timber work are you intending to keep? What are you intending to put on top of the rafters?

Since you want to use it as an office, to reduce draughts, I would probably add a layer of ply on top of the rafters, followed by the felt (tiling underlay), then the battens and tiles. This would probably mean adding extra rafters, due to the additional weight.

I agree that it itsn't necessary to completely remove the sag from the ridgeline but obviously you should satisfy yourself that there is no associated structural weekness.

I would recomend that you get a surveyor or structural engineer to look at what you have and your intentions, especially if you are intending to make any changes to it's design (such as I have suggested above). Having said this, shop around as their fees can vary considerably.

Keep us posted on your progress

 

[madachab]

Intersting that you mention boarding on the rafters, somebody else suggested that. Somebody else suggested a breathable membrane as there will be no effective ventilation in place. Of course, I don't want condensation dripping onto the computers so it's something to bear in mind.

I've put some feelers out for surveyors etc - they all seem to be quite busy at the moment just like the roofing guys

I've had a good look at the condition of the rafters and they are absolutely sound with the exception of the 3 tree branches that were used!!

I've been looking at http://www.asphaltic.co.uk for supplies, are these a recommended source?

I was amazed to count 400 tiles on the roof - a lot more than I had realised.

 

[TexMex]

I've been looking at http://www.asphaltic.co.uk for supplies, are these a recommended source?

never used them myself but I've heard nothing but good things about them.

Somebody else suggested a breathable membrane as there will be no effective ventilation in place.

Another reasonable suggestion. As a matter of personal taste, I prefer the look of ply to the underside of a membrane. It makes the place feel a bit more homely. So I'd probably sort the ventilation out by other means. But the membrane would save the work of the extra rafters, that I previously suggested and the work of putting down the ply.

400 tiles on the roof

Yes, It adds up eh?

 

[madachab]

Had a 'friend of a friend' surveyor come round this afternoon. Stone barn conversions are not his field of expertise, but he does recommend a breathable membrane for almost all exposed beam or 'cold' roofing jobs he advises on.

He was happy that boards be used on top of the rafters, and suggested uniform 3x2 timber replacements for the mixture that is already in place.

He also told me about a new rule that is coming in or already has (can't remember exactly what he said)??? That is that battens should be 50x25 and not 38x25 as I had priced up for. As we are in the North Yorkshire Moors national park, he explained that maintenance and repair do not require permission as long as we are not altering the outward appearance or obviously flouting existing laws, but rules is rules and legislation must be adhered to. So I'm glad he came round!

He also told me that lime mortar is required in this area, and also said that it is better on the ridge tiles anyway as it is not quite so brittle.

So, it looks like I finally have a plan of action. Rafters, boards, membrane, battens, tiles and then ridge tiles - simple really

Erm..how thick should the board be? Should it be marine ply?

Oh and before any of this of course I have to repair the stone work that forms the roof pitch line.

The barn is 21ft x 11.5ft, the roof section is 4.5ft high. Apparently, unknown factors not withstanding, we should have this done in no more than 3 days!!!!!!!!!!

More images here - http://www.riverside.gb.com/outbuilding/INDEX.HTM I hope to add more images as progress is being made

 

[TexMex]

This friend of a friend, seems a quite a find. Yes lime mortar is more flexible than sand/cement and would therefore be ideal in this situation (even if it wasn't a stipulation). It's lovely stuff to work with anyhow.

Marine ply is the norm for the boarding (19mm). You can then scrabble about on top of it to your hearts content. There are other materials that work, but the extra you pay for the real thing is value for money.

From your new pictures the rafters look closer than my original perception and probably up to the extra weight of the ply. This is only a guess on my part though, (scale can be tricky when working from photos), so you would be well advised to get confirmation on this issue.

3 days eh? Does that include removing the old roof and building up the gable ends? (that'll be lime mortar as well, I take it.) Mind you, with a few industrious assistants, not out of the question.

I notice you're starting to look at upgrading the electrics as well, so it could be 3 1/2 days

 

[murraysnudge]

Just a point of detail here. Tex said:

I would probably add a layer of ply on top of the rafters, followed by the felt (tiling underlay), then the battens and tiles.

Roofs with sarking boards like you propose require 25mm thick counter battening running up the roof before tiling battens may be fixed.
This ensures that any water that gets past the tiles can run down the felt to the gutter.If you don't use these then the water is trapped against the tiling batten.
The felt underlay may be either fully supported by the plywood sarking or unsupported between the battens and counter battens. My opinion is that it is better to fix the underlay over the counterbattens so that you get an air flow behind the underlay which will help reduce condensation.

 

[madachab]

Thanks

I think I understand...this is a quick side elevation diagram - is this what you mean?

http://www.riverside.gb.com/outbuilding/images/roof.jpg

 

[murraysnudge]

Almost, the order of roof components is right but you're not tiling my roof!

 

[madachab]

I had realised the tiles were the wrong way round, but I'd already saved it and closed it by then - I might not fit the roof exactly to the diagram!

We have a branch of Jewson about 3 miles away, are they good enough for the timber requirements? Should the 1" battens be tanalised?

Cheers for everbody's help - it makes me feel really comfortable about proceeding

 

[murraysnudge]

It was a good diagram but I couldn't resist the joke. I would use tanalised just like the tile battens will be so why not use the same ones? I've just had some delivered; 25x50@19p/metre. I got them in 4.8metre lengths.
Jewson's a good firm.

 

[madachab]

Asked Jewson for a price and told them I will shop around. They said to let them know what other people are quoting. Hopefully means they'll reduce if others qoute lower

A point of detail with regards to the ridge of the roof, should the boards and counter battens meet to a point at the ridge, or should there be a gap?