Leak in roof at back of property

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Hi,

I have a leak in my roof at the back of the property. I'm planning to get it sorted by professionals, but I would really appreciate any feedback/thoughts to help me properly diagnose the problem and get the right people in to sort it.

When we moved into our property (July of last year) we found that the previous owner had covered an entire wall of badly water damaged plaster with drapes. We spent £200 on a damp surveyor, who told us that it was caused by a leak in the roof and that it was historical .

Over the winter the plaster got worse, and so I decided to take it down, as it was ruined anyway. Low and behold, as soon as I did there was a drip of water from the roof. It was raining very heavily at the time, and the amount of water coming through was a small but steady drip.

Here is a photo of the back of the property, as well as a photo of the affected wall from the inside of the property. I've tried to highlight in red the affected area. I've also highlighted a window in both as a point of reference.



I've now had a roofer come around and have a look at the roof. Here are some photos he took while he was up there.



The first photo is at the back of the chimney stack, at the point where the chimney stack meets the roof. The second is the same, but this time from the side of the stack.

In the first photo you can see that the tile directly behind the chimney stack has cement in the grooves. While in the second photo you can see cracks in the mortar.

The roofer told me that this tile is no longer functioning properly, and as a result water is making its way through the cracks in the mortar.

This seems reasonable to me, and it is roughly in line with the location of the leak, but any expert feedback would be much appreciated. Does it seem reasonable?

His suggestion is to

To remove existing defective tiles and mortar from around chimney stack
To install new leadsheet back gutter and side flashing detail dressed to correct code of practise
To tile defective area back in using Redland 49 interlocking tile
To fix GRP termination bar to newly installed leadsheet

Again, is this reasonable?

I am pretty sure that some of the timber underneath will be rotten, as the laths we well rotten when I took the plaster down. The roofer said that in regard to the timber we would have to play it by ear until the tiles come up.

I've got several more roofers coming over the next week, so I shall also see what they think.

Anyway, long post, but any feedback would be greatly appreciated.

P.S. It's an 1840s Victorian terrace house.
 
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GrP term . bar :confused: anyways I would rather take the chimney down and re do the roof /gutter - than try and get a flashing onto a stucco rendered chimney like that ;)
 

ree

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The chimney stack should stay - its a valuable feature of an older house and helps to give the property some distinction. Have your flues swept and vented.

The sand and cement fillets that have been used around the stack (presumably on the neighbour's side as well), of course, require removing and making good with new tile and lead flashing.
Termination bars are unnecessary, and might actually cause further leaks. Lead stepped cover flashing and soakers, with a lead back gutter - wedged and pointed into beds - are sufficient.

Does some kind of roof parapet run up behind your stack?

AAMOI: S&C fillets can be seen on the shared ridge stack, and (i think) on the sheet roof between the outriggers.

How the main roof guttering is fixed is difficult to tell - is there a fascia board? All the visible woodwork needs attention.

If possible you will have to enter the loft space and examine the leaking area for wood rot.

The smooth rendering on the outrigger appears to be in a state of disrepair.

Your ridge has a distinct bow, probably due to the low pitch, and the extra weight of the concrete tiles that replaced the original slate.
 
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Thanks for the feedback.

I'm not sure if the joists in the loft were designed to take the weight of a person. I didn't want to risk it, so I took some photos from the loft hatch. It looks like a mess, but I don't know what it is. Fungal growth of some sort? Here are the photos.

Here is the view from the hatch


and here are some close ups




I will answer your other comments shortly.
 

ree

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Its difficult to say what the substance is:
1. possibly fungal bloom hat has been sprayed with anti-fungal chemicals. The dark staining on the rafters suggests this.
2. some kind of earlier insulation
3. dont know.

The joists will be strong enough to support you; whoever installed the insulation in the joist bays had to stand or crawl on them.
Perhaps use crawl boards?
 
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OK, so it seems that the S&C fillet and defective tiles are the likely culprit of the leak, which is good to know.

The chimney stack should stay - its a valuable feature of an older house and helps to give the property some distinction. Have your flues swept and vented.

The main chimney stack is definitely staying. I've already had that vented at the top with ridge tiles. They had been left open before and this was causing damp issues.

Large portions of the single stack have already been removed inside the property, so I'm not so sure it is worth keeping that one. I am probably inclined to keep it anyway. I think it would be a shame to remove it unnecessarily.I agree that it will need venting though, as again I think it is causing damp issues in its present state.

If I did have it removed, then how far down would I have to go?

Termination bars are unnecessary, and might actually cause further leaks. Lead stepped cover flashing and soakers, with a lead back gutter - wedged and pointed into beds - are sufficient.

The roofer did mention about bedding the flashing, but said that it would difficult on that chimney stack. I can't remember what reason he gave. I will ask him. Would this bedding (which I assume would be mortar) go on top of the current render, or would the render need to be removed first?

Anyway, it seems from peoples comments that termination bars are not really appropriate for this job.


Does some kind of roof parapet run up behind your stack?

Sorry, I'm not entirely sure what you mean here. Do you mean a little parapet wall that runs up from the back of the stack to the top of the roof, and that would separate my neighbours roof from mine?

How the main roof guttering is fixed is difficult to tell - is there a fascia board?

There doesn't appear to be a fascia board. It looks like it is fixed directly into the brickwork/render.

The smooth rendering on the outrigger appears to be in a state of disrepair.

If it is the bit I am thinking of, at the very base of the extension, then that is just the paint that has come off.

Your ridge has a distinct bow, probably due to the low pitch, and the extra weight of the concrete tiles that replaced the original slate.

This is true. Strengthening the frame of the roof to support the extra weight of the concrete is one of the jobs I wanted to get done. I may as well look into this at the same time.
 
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OK, so it's not dry rot?

I will look into getting into the loft area.
 

ree

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Venting a stack with ridge tiles will eventually cause further leaks - the typical stack flue vent is an insert that goes into a chimney pot.

The single stack is an external chimney breast, there would be, presumably, nothing to remove inside the house. The fire opening in the old kitchen would have been the only visible presence.

Look at your neighbours - they have dropped their stack.

A roof parapet is as you say - do you have one?

Whenever work is done that enables access to the gutter then fix a PVC fascia.

Why is the paintwork delaminating from the background render? Does the render touch the ground? Why the built-up yard gulley?

As emphasised above, all S&C fillets must be replaced by lead flashing.

I didn't say it was not Dry Rot. You must get in and probe the timbers and pic the stuff close up.
 
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Hi ree, thanks for the response. It is much appreciated.

Venting a stack with ridge tiles will eventually cause further leaks - the typical stack flue vent is an insert that goes into a chimney pot.

I did look at flue vents, but half the chimney pots were missing.

The single stack is an external chimney breast, there would be, presumably, nothing to remove inside the house. The fire opening in the old kitchen would have been the only visible presence.

Yes, the opening in the kitchen is the part that has been removed. All that remains is the part on the first floor, which is now a bathroom.



Look at your neighbours - they have dropped their stack.

OK, great. I hadn't noticed that.


A roof parapet is as you say - do you have one?

I'm not sure. I will have a look when I get home.


Whenever work is done that enables access to the gutter then fix a PVC fascia.

Sure, will do.


Why is the paintwork delaminating from the background render? Does the render touch the ground? Why the built-up yard gulley?

The previous owner had a climbing plant growing up that wall. I think the roots got under the paint. I'm not sure if the render touches the ground. How can I tell?

What is a built-up yard gulley?

As emphasised above, all S&C fillets must be replaced by lead flashing.

Sure. By shared ridge stack, you mean my main chimney stack? The S&C fillet on the sheet roof between the outriggers, you mean that ridge on my flat roof that is on the right of the photo?

I didn't say it was not Dry Rot. You must get in and probe the timbers and pic the stuff close up.

OK, understood. I can't say I'm looking forward to that job!
 
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The stuff on the rafters looks like a wasp nest that's fallen down.
if if feels like paper and there is "honeycomb" discs inside, it's a wasp nest.
 
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I've now had a better look at the roof, and it seems that there is no roof parapet. What is the purpose of these? I've seen them everywhere, but couldn't work out the purpose of them.

I'm planning to get some 6ft scaffold boards for other purposes around the house anyway. I assume these will suffice for going up into the loft.

I've now had another two quotes on the problem with the chimney at the back, which are as follows:

First quote

Strip tiles and faulty cement filet to area around leaking chimney to rear of property.

Thereafter install new lead back tray and cover flashings to be chased into chimney,
wedged and pointed.

Replace tiles on completion.

Clear all debris and leave site clean and tidy.

and second quote

Remove existing flashing, cement fillet to rear of chimney and dispose. Remove defective tiles.

Lay new 18mm osb smart ply to sole of lead back gutter behind chimney with 25mm tilt fillet set 150mm from sole.

Chase render 25mm deep to sides and rear of chimney to accept new lead flashing.

Fit new 300mm code 4 milled lead sheet flashings to chimney sides, dressed into wall 25mm. Wedged using hall clips, sealed using lead sheet sealant.

Fit new code 4 milled lead sheet back gutter to chimney, returning 300mm up roof pitch over tilt fillet, with water check to top edge, 100mm upstand to chimney. Returning 150mm past chimney, welded out of situ to fit roof profile.

150mm code 4 milled lead sheet cover flashing installed over back gutter, welded at corners.

All lead work to BS6915

2 coats of patination oil.

They both seem to be in line with Ree's recommended course of action. Although, the second is a bit dearer. Any feedback on these?
 

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