Leak into roof of attached garage

[AnthonyL]

The house is a detached bungalow, late 1960s build, with the length of the roof running from front to back so that the gutters run also front to back. Similar to

looking from the front.

A brick garage is on the left hand side and extends a few feet (enough for a side door plus a bit). The roof is felted - see other post re moss problems.

Water is getting in at the end of the bungalow and around the side door.

I'm not fully up with the bulding terms but the verge under the last two edge tiles are cracked, and the area underneath and therefore to around the top of the garage is coming away. It's a sort of render. The best I can do to explain it is that it is similar to the unlabelled black area under the verge at

Tips, clues how to diagnose and how to repair needed.

[Tricky Dicky]

A photo of the actual area in question would be a lot more helpful. One issue with built up felt roofs is that a leak manifesting itself at one point could be due to damage elsewhere and water moving between detached layers. Frankly if that roof has been there since the sixties it is well past it?s sell by date especially if it has felted chipboard boarding common at that time. I suspect you may find yourself chasing the problem and in the end replacement with 18mm plywood boarding and modern flat roof membranes will be the only way to get peace of mind.

Richard

[Andrew]

Nothing wrong with OSB3 for flat roofing. Also available in T&G 8x2 versions which is ??essential if you are going to have fibreglass otherwise you must support all edges on noggins.

18mm ply is generally only used for flat roofs on residences where building control might be involved.

[AnthonyL]

Photos are at:

The roof has been refelted since the property was built but probably not in the last 15yrs.

[Tricky Dicky]

You could have a number of problems there. The first thing I would look at is the lower rows of tiles on the main roof, that is a worrying missing piece of tile alongside some rather loose mortar verge. If water is getting in there you may find the sarking perished and as the felting seems attached to the original eaves and barge boards, damaged sarking will simply allow water to work its way down and produce those damp patches in the garage.

When we moved into our bungalow it was linked detached to next doors by a carport. The previous owners had UPVC cladding covering the original eaves boards which simply masked problems similar to yours on all corners but particularly at the interface of carport and our roof with the carport felting extending under the second row of tiles on our roof. Because we had problems on the other side of the roof with perished sarking not to mention a leak, we decided to replace the roof and this meant approaching our neighbour. He had multiple problems with the carport roof and was not prepared to try to repair it. He was therefore quite happy to remove it and thus allow rotted fascias to be repaired, we were quite happy to have the link removed as it then made us a detached bungalow as well as getting things put right. On our side any rot was limited to fascias and only a couple of rafters showed any water damage which was as well as they are in fact trusses. On my neighbours side where the carport interfaced similarly to ours the water damage was far greater particularly at the roof overhangs where water was getting into loose mortar verges and perishing the sarking and damaging the false rafters underneath and required significant repair and splicing in new timber.

Richard

[Fredxx]

The second photo indicates this has already been repaired. All I can suggest is a thorough clean and for a temporary repair more felt in conjunction with suitable bitumastic sealant as glue.

[AnthonyL]

I'm not sure what exactly the "this is" that you are referring to.

[Dave Plowman (News]

Looks like it could do with a decent bit of lead work there.

[Fredxx]

The felt "this is coming away" looks different felt to that used anywhere else.

[Fredxx]

I do think of felt as a poor man's lead.

[Andrew]

The original garage roof would have been an exact rectangle, I suspect. Then that plastic-roofed lean-to was added and the garage roof extended to join on to it, and it looks like some repair work has been done with torch-on felt onto what may have been damp timber.

The felt curls up the 'gable end' of the lean-to, but not where the extended bit of garage roof wraps around the corner of the house. This is part of the problem. You need an upstand where ever a flat roof meets a vertical wall or structure. You have been visited by Messrs Bodge_It_And_Scarper, Quids_We_Win_Pounds_You_Lose at some point.

Is that timber or brick that can be seen where one of your red arrows points to ?.

Looking at the damp patch, there is also inadequate fall to the garage roof anyway, resulting in ponding in the area where the leak is occurring. This is a double whammy at this time of year because you don't know how much damage there is until you can carry out a major investigation. Until then a big tin of Thompsons emergency wet patch might keep the rain out.

Since this is just a garage I would pull down all that bowed plasterboard (artex with asbestos ??) so that the timber can dry out and you can see where it is coming in. Also means you can position a suitable bucket.

[AnthonyL]

Thanks. Once I find my outdoor ski gear I'll look more closely at what may have been old and what may have been new.

I've got a roll of felt, originally intended for a shed, and some bitumen. What's best to do? Cut off the loose felt and re-cover? How best to clean?

Can the felt be heated up first and is there any benefit in so doing?

[Fredxx]

You really need a dry surface to paint any roof felt adhesive. Warm felt is more pliable and more likely to take the contours of edges without cracking or trying to revert to their former flatness.

As others have said there are liquid treatments. These are simple to apply. My instinct is that they won't last so long.