Slate roofing insulation

[StevieB]

I have just opened up the roof space above my dining room / kitchen by putting in a loft hatch. These are in the form of an extension on the back of the house and cover an area approx 10 feet wide by 20 feet long with an apex ridge about 5 feet high. The roof is slate tiles but with no membrane between the battens and the slates - all I have is sky, slate and loft in that order

I want to a) make sure the space is waterproof and b) insulate the loft. Is my only option to remove the slates and battens, lay down roofing felt then rebatten and slate or is there a better way? A friend suggested getting a company to spray foam insulation but I wasnt sure they would spray straight onto slate, and what happens if I need to replace the slates at some point in the future? Anyone any experience in these type of companies? Cost? Or anyone any bright ideas about how to ensure the roof is waterproof?

The house is old (1880ish) although I doubt the roof is original, and I have a few slipped slates which need replacing but it can wait until spring if I have to strip the roof off!

Cheers,

Steve.

 

[Russell]

I think you can get a foil backed membrane you can attach to the rafters to line behing the slate. However it is important that your roof space is ventilated otherwise you will have a damp problem. Older houses often just have the air gaps between the slate to vent them. Newer house have vents built into the eves ?. You can insulate the loft floor to about 10 - 12" thick but agian not right up to the eves or where the ventilation is.

 

[OLD]

You could have a look at manufacturers info on the net
http://www.insulateonline.com/index1.htm?flatintro.htm~main
Go to products pitched roof .To understand the problems and various solutions.

 

[ike]

Steve,

I was faced with the same problem a while back. Whilst keen not to go the whole hog due to the expense, my conclusion in the end was to re-roof as my slates were also quite poor, and all other solutions seemed like bodging.

Roofer fitted high density fibreglass 2" insulation batts between (4") rafters. He used a breathable textile-like membrane instead of normal roofing felt. I can't remember the make - it was white and German made (and expensive!). He also fitted slate vents.

I'm glad now I re-roofed. The trouble with just fixing up the inside of a roof and not the rest of it particulalrly with slipping slates, is that leaks can go undetected for longer with more serious consequences as damp and rot get into the timbers.

After all it's a fairly fundamental thing in our life to keep a decent roof over our head!

Ike

 

[garywayne]

Steve, I haven't had anything to do with roofing for over 30 years, so things may have changed.

I would have thought that you are going to have to strip your roof to waterproof it properly. Sorry.

 

[cd]

Hi Steve,
I've not had the problem myself but my sister had a similar problem with her last house. She opted for the spray on stuff from a company called Renotherm and was very happy with the result. It sticks to the slates to keep them from slipping and adds considerably to the insulation. She actually ended up having a spiral staircase installed and using the loftspace as small office.

HTH

cd

 

[Jake]

Really really don't do the spray insulation thing. It's cheap in the short term, but once done your roof is stuck on, replacing the slates when they wear out is very difficult, the timber is encased in foam without any water barrier under the slate - so damp gets on the timbers but the timber doesn't have any air circulation to dry it out again, which means the potential for rot shoots up. It's a total cowboy 'solution'.

 

[StevieB]

Thanks for all the info, pretty much confirms what I thought! I dont like the idea of the spray stuff to be honest. Looks like a re-roof is on the cards. Fortunately its only the extension at the back not the entire roof so it may well be a DIY job in the spring. Most of the slates look OK and can be re-used with a little luck.

Cheers,

Steve.

 

[Anonymous]

Really really don't do the spray insulation thing. It's cheap in the short term, but once done your roof is stuck on, replacing the slates when they wear out is very difficult, the timber is encased in foam without any water barrier under the slate - so damp gets on the timbers but the timber doesn't have any air circulation to dry it out again, which means the potential for rot shoots up. It's a total cowboy 'solution'.

Totaly agree

This is just another way to market tacky smelly 2 pack chemicals at grossley inflated prices and palm them off on unsuspecting public

I bet they dont test the rafters purlins laths etc to see if theyre dry first before they get their spray gun going :roll: white van cowboys only want your money fast then on to the next unfortunate victim then off to marbella, **** the consequence's. Imagine the scenaroio in summer when that damp timber gets cooked in the sun, breeding ground for fungus's mould etc not to mention fire risk as well. T'would be spectacular if the timbers all rotted and the whole roof suddenly caved in though :roll: I almost had a roofer fall through my roof once, nail rot to be expected after about 100 years.
Any decent surviving old roof has been well ventilated and maintained over the years, especially clear guttering and downspouts, replacing storm damaged slates immaedialetly, regularly check pointing on ridge tiles, chimney flashings etc etc. Ike and Gary have the right idea-traditional solution ie re roof with insulation and felt dpm added; you could possibly re-use the slates (or tiles) not sure what slate tiles are; if theyre original 1880 slate and starting to delaminate better scrap them and use new ones do a proper job of it. Costlier at first, but also peace of mind, no crappy bodging and future piecemael "repair" jobs, plus it adds genuine value to the property (unlike upvc acessories as the lying estate agents tell us)

:lol:

 

[Anonymous]

Thanks for all the info, pretty much confirms what I thought! I dont like the idea of the spray stuff to be honest. Looks like a re-roof is on the cards. Fortunately its only the extension at the back not the entire roof so it may well be a DIY job in the spring. Most of the slates look OK and can be re-used with a little luck.

Cheers,

Steve.

8) 8)

 

[StevieB]

Ah, a slight development The only reason I got to see the loft was I had to cut a hatch for the central heating that is going in. Looking at it from the inside it was awfully 'light' at one end - as in daylight light :?
Went and had a look, poked a slate and sent 5 slates slithering down into the guttering - bad case of nail rot :roll:

It's going to have to be a re-roof. :evil:

Mr Spanton - by slate tile I meant the cement tiles that are meant to look like slate. Cheaper than natural slate and interlocking so easier to fit. Only problem is I am not sure I can get away with that in a conservation area - our house lies just 4 meters inside the area which stops next door.

Thanks for all your help everyone,

Steve.

 

[Anonymous]

Is that eternit ones?
I was going to get them but the roofer didnt recomend them as they tend to cup after 7 or 8 years of sun aparently :lol:

 

[StevieB]

Yes, it was going to be them - its the trade name of Marley tiles. Major manufacturer and they have a 15 year guarantee if fitted in accordance with their instructions so I am surprised to hear you say that. Which ones were you advised cup? also, what did you go for instead?

Cheers,

Steve.