Help Needed with Leaking Roof

[wcavanagh]

Doing up a cottage we bought recently, on stripping ceilings and walls back to stone, found that where the tiled roof meets the flat roof water has been coming in. It has damaged the bottom 4 rows of wood that the slate tiles are nailed too, and looks like they need replacing.

Do tiles have to be lifted from the top all the way down to get to bottom rows?

Also I would like to redo the flat roofs, they are quite large so wondering what the best options are? GRP or Rubber stuff?

Some photos?

 

[catlad]

Well if you are not going to strip the roof then you will need a slate ripper to remove the slates, and if you are going to diy the roof then rubber is easier to do.

 

[wcavanagh]

Slate ripper looks like a great idea, as I have to do it myself I think this is the solution. Thank you very much, off to watch some videos on using one.

 

[chappers]

the problem you will have though is that you will either have whole rows of strapped slates or you could use jenny clips.
You say that the bottom four slate battens are rotten, is your problem where the flat roof runs over on to the slated roof in the 5th picture, in which case you will be ok as you will be able to strip them off on a raked angle to the bottom, you will need a slate ripper to get the last slates on the raked angle off though and don't forget to drill a second new hole and nail on those slates when replacing them.
With the flat roof the biggest issue I can see will be weathering back up under the slates that come down to meet it.
I would say that the ridge and the abutments where that pipe is coming out need some attention too.
Now might be the time to bite the bullet and re-do the whole lot, the slates look in pretty good nick and could be re-used

 

[wcavanagh]

Thank you for the detailed reply. Indeed just where the slate roof meets the flat roof, for the whole horizontal length is where water has been let in for over 1.5 years while the place was empty. From inside now I took ceiling down, I can see the timber boards are badly rotten and soft to the touch. Its only the bottom 4 rows. Also as you rightly say at the ridge where the chimney is there is also water getting in, the pipe was the old mains cable supply, I will remove this, and repair, and repoint around the chimney. I will remove the bottom 4 rows of slates and see what happens. I was planning on using slate hooks to hold the row I will not be able to nail back in.

I am very short of money at the moment, so it is all DIY. I have lots of experience with renovation etc. but have never done any roof work before. When the tiles are off, do I need to put some kind of transition material under the tiles down to the flat roof? At the moment its cracked black tar looking stuff, leaking.

I plan to strip the flat roof also and replace with maybe rubber.

Cheers

 

[chappers]

You really need to do both at the same time and lap the flat roof material up underneath the slates.
Sorry just to clarify are the rotten timbers along the long roof length as in pictures 2,3 and 4 as the slate covering along that whole length looks sound, this would indicate that the leak is from somewhere above and running down.
I note you are in Scotland and say the bottom boards are rotten, do you have weatherboarding between your rafters and the roof covering. My guess is your problem comes from above, further up the roof and water is running down and damming up behind the bitumen of the felt roof, hence why the bottom boards are rotten.
The only way to find out is to strip off the bottom rows of slates, I would go above the bottom four rows and have a look, you will get a better idea of what is going on and if it is coming from above you will probably see evidence of where the water has been running down from.
I would then replace the flat roof, lapping that roof covering up the pitched roof a couple of courses before replacing the weatherboarding and then putting the slates back down.
Slate hooks are OK but you would be better off with jenny clips as they give an invisible finish and are much better if you are in an exposed area.
Feel free to post some more pictures once you have the roof stripped off. Could you post another picture of the roof as a whole from ridge down to the flat roof

 

[wcavanagh]

Thank you again. I will take some more photos in the morning, from inside too, so you can see what I mean about the wet wood. We have 2 flat roofs with what seems to be the same issue. I thought maybe the water was coming in the cracks seen in the curve between the flat root and the slate roof. I will do both as suggested at the same time. Just trying to plan the job as best I can. Indeed I am in Scotland and we are quite exposed here, get some strong wind and sideways rain, so hooks are no good? Would I need just the one row of jenny clips the same as I would slate hooks? As I need to work out how many I would need.

Cheers

 

[chappers]

that could well be the issue, but when you take off the slates, which you will have to do, when you replace the flat roof anyway you will see if there is obvious signs of water coming from above.
Some pictures of the inside and a shot of the whole roof would be useful.
You would just use the jennys on the slates you can't nail as with the hooks, you would need two per slate and they're not the cheapest. They clip into the nail holes on the slates and the wire bits fold flat so you can push the slates up under the other ones and then swing down over the top of the battens. You may need to use your slate ripper to help guide the top of the slate up so the top edhe sits over the battens above. It's quite awhile since I have used them but there are comprehensive instructions in with the pack. The one thing with them though is you would have to remove the two slates above if you needed to remove the jennyed slate to adjust it's position, but if you have rows off you can always do a trial run on one on a lower row before you cover with the slates above.
The thing with slate hooks is if the wind catches the slates they can swing on the hooks sometimes and slip off, but you could also use two per slate

 

[wcavanagh]

Thank you again for your time. I have attached some more photos to help you see what I am facing. Looking up I cant see any signs of water from the inside, and I thought it was the bottom 4 battens but in fact it is the bottom 2. And into the flat roof section.

I am hoping the main beams that span the room are not too damaged, the ends looks wet but maybe OK. I will setup some lights so I can have a proper look.

 

[chappers]

yeah certainly looks like it is from the flat roof junction and the rot has just spread from there, so looks like that needs addressing at the same time as replacing the close boarding. The general sate of the roof doesn't look too bad apart from a couple of slipped slates, but the whole ridge looks like it could do with some attention, wonky slates etc and the abutments around the chimney look a bit dodgy, consider leading these rather than flaunching and maybe ridge and hip tiles instead of the capping.
You've got a fair bit to sort there to sort the flat roofs and a bit at the ridge, when you start taking some of the slates off you will probably get an idea as to how sound the roof is, nails etc. But don't discount taking the whole lot off re-felting and battening and relaying the slates, if it looks suspect.

 

[Doggit]

I'd go along with Chappers to bite the bullet, and re-roof, but as you seem to be a reasonably proficient DIYer, I'd be inclined to do the flat roof in fibreglass rather than rubber. You need to structure the job so that it's done in stages, as the fibreglass needs to go up under the lower row of slates. But at the same time, you need to replace the rotted boards and joist ends before you can do the flat roof. And it looks as though the top of the walls under the rotted beams needs a little work on it as well. And I'd use a breathable membrane under the slates rather than felt.

If you can poke a screwdriver into the wet wood, then they need replacing, but if you don't, then the danger is that the wet rot might change to dry rot, and then spread through everything.

I know moneys short, but if you've got to do the flat roof, and you've got to do the lower rows to be able to replace the close boarding, then it's worth going for broke. It'll need doing sometime, and it'll improve the water tightness of the house, and improve it's value. If you strip the roof, then you're just swapping the cost of the slate nails for the cost of the jennys, but you'll need extra for the breather membrane of course.

 

[chappers]

Indeed and the slates look pretty sound so you will be able to re-use most of them.