Reroofing Question: Slate reuse

Hi all,

I’m pricing up some roof repairs and considering a full replacement. The existing slates have already be relaid once when the roof was felted – I’d guess this was done about 25-30 years ago.

One company has suggested reusing the existing slates but another has said that they can’t reuse them as they have already been relaid once and can’t be used again.

Does anyone have any advise or experience they can share?

Yes we are having our roof done after 50 years, job quotes came in at 8.5k and 9k for new slates total job. Next door similar house reused his slates and it was 7.5k. So only 1k saving, our slates are shot I have repaired a few over the years and the membrane is shot underneath.

We may upgrade to clay I think it’s a grand more but they hold their colour.

Good roofers are busy atm, as are all trades, we ‘ve waited nearly a year.

Depends on condition/age of individual slates, not whether they have been relaid or not.

I helped a friend reroof his house in Cumbria about 40 years ago. Warning: this is a DiY account and may or may not follow proper practice! It had Buttermere slates (thicker and less well formed than Welsh slate). Many of the slates had worn the nail holes bigger, in some cases meaning that the hole reached the edge. We shortened any slates with serious damage (placed them over an angle iron where the new top would be and hit the part to be removed with a hammer. Then drilled new holes. Buttermere slate is used in reducing courses, ie, the slates get smaller towards the top, which means you can accommodate cut-down slates. Since the slates get smaller, he bought two courses of secondhand slates to put into the mix.

As @Dickeyboy says, it depends on their condition and how roughly they’ve been handled in the interim.

There are several grades of roofing slates, the best whether from Wales or the Lakes are very even. As you go down the quality scale the slates tend to get thicker and/or have imperfections like ripples.

Generally there are three “styles”: random width/random height – common in the Lakes, less so elsewhere; random width/even height, can’t remember seeing this in many places but have roofed one house in Wales in this manner; even width/even height, possibly the most common.

I remember scaffolding a barn in Kirkby Lonsdale, it was 100ft long and had just 30 slates on the bottom course! Absolutely effin’ massive things. The top course was something like 16″x12″.

Edit: Should say that I was a scaffolder not a roofer but obviously while you are up there you ask questions and take note of things.

Good practice is to reuse. You will usually need about 10% more slates as they resizie them after stripping.

Had a whole new roof put on in January. The slates on the back of the house were only about 10-15 years old but cheap crap. Roofer refused to even try and reuse them as they were only good for the skip and he’d not want to put his name to the job otherwise. Front slates were original to the house so 1908 and clearly had seen a good life.

In the end I went for the best I could afford (Spanish slate from memory) on the whole roof and new membrane and 70mm insulation. The attic rooms are now positively tropical.

BiL is a roofer. Depends on age and condition. We did our roof last year and hoped to reuse 40% but ended up doing full replacement as they were going soft and not worth putting back on, Scottish slate in a conservation area. His advise as he is sitting next to me would be replace.

I have a slate roof from 1905. Extension meant all slates came off. The front road main pitch is using the original slates again and good for another 100 years, but removing does mean that about 50% get broken or holes have enlarged or other chipping issues. New Welsh spotted slate for the side and back. Slate is expensive – reuse as much as you can. As a novice I was a little amazed that you only see about 1/3 of slate or something daft, I was very surprised how big and heavy the original slate was. (I was very lucky to have a contact from slate trade retiring with a storage unit full at mates rates) Good luck OP.

We may upgrade to clay I think it’s a grand more but they hold their colour.

Eh… Slate doesn’t lose its colour.

i’ll be reusing as much as i can when i reroof mine, its westmorland green so lasts well. getting hard to get hold of now and is very expensive as well.

its probably 20 years since i’ve done roofing work but we quite often reroofed and reused slate that had been on that long it was held on with wooden pegs hooked over the battons instead of nails. was quite common to find the bottom course would be 2 foot + long slates, quite wide and just fixed with a single wooden peg.