Small Roof Refurbishment.

[Tom B]

Team;

I have an up and coming project for the summer, or at least a period of nicer weather.

My house has small porch over the front hallway and downstairs loo. The house is a 1999-2001 built job with timber facias and soffits. The roof is pitched with Marley tiles (approx 30) over traditional bitumen type felt, there are no gutter tray / eves protectors. This small roof has had no work since being built (other than a small amount of pointing around the flashing). There is no internal access to the roof space / attic.

The issue is that the felt has rotten around the bottom of the roof and no longer guides the rain into the gutters causing the paint to flake etc
The plan is in around 3-4 years to have the facias and sofits replaced all around the house, including the main roof.

My initial plan was to just get some eves protectors and slip them under the bottom row of tiles and tart up the paint before the wood gets damaged.


However; I am generally not one for bodging and generally like to do a job properly.

I feel a mini project coming on. My current plan is to strip off the existing tiles, numbering them in rows, stacking them up, leaving the flashing on.

I expect that there is no insulation in the mini attic above the hall and loo - I couldn't find any when I cut an 8" hole for a light. - This might explain why despite heating it feels colder than outside in the downstairs loo.

Stripping off the battening and old felt.

So the plan is to insulate the attic space from above, probably with celotex type stuff between the ceiling joists then another layer at right angles allowing space for a draft to blow.

I have a roll of that new modern fabric type underfelt left from when I put a "proper" roof on the conservatory so was planning to use that to line the roof, install gutter trays, then re-install the tiles / battens, verge.

I could then replace / repaint the facias and gutters if so wished / depending on condition.

Does anyone see any issues with my proposed plan?

- The tiles are around 25 years old and while weathered don't show any signs of deterioration.

 

[MikeG]

Architect here, so I've seen hundreds of jobs like this.

My only comment on your plan is that there doesn't seem to be any good reason why you'd number the tiles or expect them to go back in the same place. Save yourself the trouble. You didn't say whether you were using new battens or expecting to re-use the old ones. Definitely replace them, as the old ones will be damaged by removal, and obviously use new nails.

My final comment would be to please ensure you have safe access. A scaffold under each eave is essential, and ideally with the bottom edge of the tiles at about knee height.

 

[MikeG]

Oh, as an afterthought. Don't buy gutter trays, but just cut some strips from your roofing felt for the purpose. I think bought stuff is about 400mm wide, from memory, so just select some better felt from high up the roof and cut it into 400mm wide strips. It's the same stuff.

 

[Tom B]

Architect here, so I've seen hundreds of jobs like this.

My only comment on your plan is that there doesn't seem to be any good reason why you'd number the tiles or expect them to go back in the same place. Save yourself the trouble. You didn't say whether you were using new battens or expecting to re-use the old ones. Definitely replace them, as the old ones will be damaged by removal, and obviously use new nails.

Thanks for your comments;

I was going to replace the battens, I have a bundle left from building a trellis.

The reason for numbering the tiles was indeed to stick them back where they came from, to avoid new cuts and new tiles (as long as I don't break any). I don't have an issue with cutting them but a new tile amongst them would bug me! I was hoping if I put the new battens back in the same place as the old battens it should all go back together... No?

My final comment would be to please ensure you have safe access. A scaffold under each eave is essential, and ideally with the bottom edge of the tiles at about knee height.

Access shouldn't be an issue, it's low single story and I've got access to a trestle platform - it probably won't be HSE approved but it's better than a ladder. That said when I stand on the roof to put the Crimble lights up or clean the widows I jump off anyway.

 

[Tom B]

Oh, as an afterthought. Don't buy gutter trays, but just cut some strips from your roofing felt for the purpose. I think bought stuff is about 400mm wide, from memory, so just select some better felt from high up the roof and cut it into 400mm wide strips. It's the same stuff.

I was thinking these sorts of things? From the conservatory roof they are more rigid PVC and despite a south facing aspect do not appear adversely affected by the sun.

 

[MikeG]

That's the proprietry solution, and of course that's perfect for the job. However, roofing felt is a perfectly accepable alternative. Entirely up to you.

As for the tiles......just get your battens back in the same place and the tiling will work. The cut tiles will be the only ones which need a set place on the roof. All the others can go anywhere. The thing I would worry most about an amateur doing on a roof is the undercloaking and pointing. The rest is easy.

 

[Tom B]

Thanks again for your thoughts.

There shouldn't be much pointing, it is something I can do, I'm just slow.

From what I remember from putting the verge back on after a storm a few years ago..... Undercloaking isn't a feature on this construction. The battens just project over the edge of the roof and are capped with verge caps.

It is probably something to look at adding in, and not something I had considered - I should have because I remember adding it to my dads garage roof when we replaced that and being cockahoop it came out at bang on 50mm when we added the barge.


I was also planning on putting a duct across the attic while I had access to allow me to send a cable for an EV charger across from the meter box side to the car side so in the future should I so desire I can more easily install a charger.

I see lots of people / adverts promoting insulating between the rafters either with some spray stuff or using 4" celotex boards, it doesn't seem to make much sense to me as I understand a good loft should have a good draft? What are your thoughts on that. If it makes sense and has a benefit now would be the time to do it.

 

[CXRAndy]

It's getting a material which is UV stable for the eaves. Old felt will likely breakdown quickly and potentially cause issues. Use the correct stuff, it's only a small area overall

 

[CXRAndy]

Celotex between the rafters is a good idea, you need to have 25mm minimum gap between the felt and celetox to all air movement from eaves to ridge.

 

[MikeG]

It's getting a material which is UV stable for the eaves. Old felt will likely breakdown quickly and potentially cause issues. Use the correct stuff, it's only a small area overall

Fine...but the correct stuff is also made of felt. In fact, it is identical to roofing felt but sold in a narrower roll.

 

[MikeG]

Celotex between the rafters is a good idea, you need to have 25mm minimum gap between the felt and celetox to all air movement from eaves to ridge.

With breather membrane, you don't need air movement from eaves to ridge. You don't need eaves ventilation (or ridge ventilation). You do, as you say, need a gap to the membrane, but that's actually primarily so that the membrane can drape properly between the rafters and allow any wind-blown moisture that gets through the tiles to get down to the eaves.

 

[MikeG]

I see lots of people / adverts promoting insulating between the rafters either with some spray stuff or using 4" celotex boards, it doesn't seem to make much sense to me as I understand a good loft should have a good draft? What are your thoughts on that. If it makes sense and has a benefit now would be the time to do it.

Don't spray, whatever you do. I've never seen it be anything other than an unmitigated disaster.

Celotex is approximately twice as efficient an insulator as fibreglass/ mineral wool. It is also many times as costly. If you've got room, use fibreglass (Earthwool, as was, is the one I'd suggest......I can't remember what it's called now). One of the advantages of fibreglass is that it can be easily made to fit very snugly, whereas Celotex is difficult to get a good fit with. You should be looking to get 250mm + of mineral wool/ fibreglass thickness, or 130 of Celotex/ Kingspan (PIR insulation). For context, one of my rooves here has 750mm of mineral wool, and others have 170 Celotex between rafters and 50 across the underside.

 

[Tom B]

Thanks again.

For this job I have kept / acquired some off cuts of 4" and 2" Kingspan all decent sized. The In-laws have a few half sheets left over saved for me. It's surprising how much you can pick up for free off Facebook or by seeing it at the side of skips and asking. (I've got a couple of 4x4 sheets for free like that) So hopefully costs should be minimised to at the most a sheet or two. When I've used it in the past I've sealed the joins and any wounds with sticky aluminium tape.



So if I replace the old black felt with new breathable membrane then I don't need as much ventilation / draught?

If so that news will certainly make replacing the soffits much easier as currently they have long vents running behind the Facias. They're horrible to keep clean and would be a faff to fit. I could just pop in a couple of the small round vents in.

In a few years time (2-3 when mortgage is paid) I'm thinking of solar panels and replacing the timber Facias and soffits (hipped roof). I'm thinking then the roof will then be about 25yra old so the plan is to strip the roof and replace the felt with the new stuff and install a dry ridge. Before solar panels and new facias.

Itll be more expensive but it seems to make sense while the scaff is up and before putting panels on the roof.

That said that'll be a job for a pro co.


The porch is a smaller job..



*The sky cable has gone!

 

[cyberknight]

I am just getting a roofer in to do the roof verge , going for the caps as the old wet verge is falling off and we have a bit of damp in the bedroom wall in that corner where its worst . getting someone to do it as no way im getting up a ladder to even attempt in

 

[MikeG]

So if I replace the old black felt with new breathable membrane then I don't need as much ventilation / draught?

If so that news will certainly make replacing the soffits much easier as currently they have long vents running behind the Facias. They're horrible to keep clean and would be a faff to fit. I could just pop in a couple of the small round vents in.

Correct. You won't need ANY soffit or fascia vents. It's the whole point of this stuff.