External Pic of Damp Problem

Brick slips on external wall insulation. They are eaves trays in the gutter , Tiles are short of the gutter by approx 30 mm. Eaves trays are bridging the gap. Theres a half tile course at the eaves.

Sorry I wrote cavity by mistake. Your description is correct. Im not sure if there's cavity wall insulation and im not sure what the external insulation is.

Theres a half tile under the bottom row of tiles. Wil put other pics up asap. All elevations are open to the elements. Insulation added 2 years ago, property is approx 60 years old.

Eaves and gutter detail...

Yeah, what is that 'gap-jumper'? It certainly doesn't look like an 'industry-standard trim'!

They are eaves trays / carriers. Sold for the purpose of repairing roofing felt where it tends to fail at the first row of tile and soak the wall below. You can push them under to maintain waterproofing without redoing the roof.

Some thoughts for the mix, as more info comes out... (overlap with DC above)

- the "gap jumper" is plastic eaves guard. It's an excellent detail, when used appropriately. Historically, a band of felt was laid under the last row of tiles/slates and folded down into the gutter, but this would rot within a few years on the external part, and often puncture on the inside part, where tiels/slates had pressed on it. That is the worst part of a roof to get a "puncture" as it sees all the rain from all the roof above it. So the rigid plastic eaves guard is supposed to replace that, hidden under the tiles/slates, and projecting the roofing felt/membrane across the wall head, into the gutters.

- theoretically, in the photo, there is a bridge across, but I wouldn't trust that there's no water getting in at this point, as the eaves guard is NOT designed to be the prime rain shield, it's the backup to shed any leakage caught by the membrane, and shepherd it out to the gutter.

- the eaves guards should overlap one onto the next by 150mm, but as the photo shows, that overlap point has lifted, (not held down by tiles/slates passing over which should be the case) and so very likely wind driven rain is getting in. Basically, that eaves guard is a good construction item, but wrongly used, and likely to be failing to some extent.

- another thought occurs as I write the above line, if the eaves guards were in deed just pushed in from the outside, and no tiles removed to fit them properly, they will not have lapped UNDER the existing roofing felt/membrane, so any water that gets to that felt/membrane layer will not run outwith the roof, but be forced into the roof void by the eaves guards, which are doing the opposite to that for which they are designed.

- equally concerning is that the gutter appears to be full of water (blocked or running the wrong way). All gutters will leak if holding water, and I would guess when there's heavy rain, the gutters empty over the house walls. To me, that explains the widespread water damage externally.

- I'm favouring this gutter problem also because whoever was happy to shove the eaves guards under the tiles, will not have cared about correctly re-fitting the gutters to fall to the running outlets.

- if there is water regularly running over the outside face of the walls, it will find a way in through the slips and EWI, which is not designed to be a river bed.

Based on the limited info to hand, I would suggest the gutters need sorting with urgency (cleaning/correcting the falls), and that the bottom couple of rows of tiles be removed, check the membrane below, and re-install with the membrane passing over the top of the eaves guards, and additional tiles to correctly project over the eaves guards and say 30mm into the gutter. That's a bare minimum to have a correctly installed roof. Give it a year to dry out, and then review if there's still damp ingress.

Theres no membrane under the tiles and there's only 2 areas being affected. The whole walls are white where I have highlighted on my sketch. Its like something has been done different in these 2 areas.

That window sill looks like it gets a good wetting (green)

My take is that the eaves tray has not been fitted properly and maybe the wrong size. Rain coming down the roof is being blown in under the tiles and getting into the insulation that way due to insufficient cover. The tray overhang is so close to the edge of the gutter that it is overflowing onto the brickwork and causing efflorescence. Solution could be to remove the lower run of tiles fit a bigger wider tray (suspect such a product is available for jobs like this) that covers the insulation. Found this video which shows what I mean.

https://www.youtube.com/watch?v=zVAvF5fNrm8

<blockquote><cite>Posted By: GreenPaddy</cite>not 100% sure I understand "...it's right up to the boundary..." but it certainly looks like the eaves guard is covering almost the entire gutter, so rain will tend to flow over the gutter and down the wall. Adds a bit of weight to the soaked wall possibility. Not saying that's the only issue, but it will make matters much worse.

Plus the gutter looks full of leaves/gunk as it's not easily accessible for cleaning. Looking at the various photo's, it appears to be a less than professional job.</blockquote>

X = neighbouring property with white stains on brick slips . Tick = same elevation with no stains on brick. This is the north west elevation on my sketch.

Posted By: djhNice video. It's good when you see somebody who cares about what they're doing :)

That is what I thought as well.

A contrast to contractors resurfacing our road a couple of weeks ago. They dumped a load of road planings in our splay without permission and then made a mess of cleaning it up when I asked for it to be removed. In doing so they removed part of the top surface of our splay. There is a surface water drain outside the splay and there was some weed growing out of the side of it. They were preparing to lay the tarmac over the weed until my wife pointed out to him if he was going to remove it. He did so with a scowl after some persuasion from her. I am waiting for reinstatement of the splay surface and if nothing gets done next week I will complain that they fly tipped to see if that gets some action.

<blockquote><cite>Posted By: Dominic Cooney</cite>Could there be a different treatment to the roof on that property? Has it been re-roofed with a membrane? is the picture provided of the underside of the roof taken above the affected area or is it the roof above an unaffected area, e.g. next door?</blockquote>

Same roof on adjoining property, no new tiles and no membrane. The internal picture is of the roof and is over the affected area highlighted on the elevation that faces South West on my sketch.

The white is probably efflorescence - soluble salts crystallising on the surface, as water comes out of the brick (slips), evaporates on the surface, thus 'disappears' from liquid's POV, creating a tiny vacuum in the caplillaries, which draws more water out to the surface - a one-way pump. Any dissolved salts in the water within the brick (slips) is thus drawn continuously out, crystallises on the surface.

Where did those dissolved salts come from? In rainfall impinging on the wall or draining off the roof? (impossible - rain is basically pure distilled water); In the brick (slips), as manufactured? (unlikely these days, though common in cheap bricks traditionally); In the sand used for pointing? Most likely. Salt-laden sea-sand shouldn't be used for bricklaying unless well washed as supplied; The water in the mortar mix? Unlikely - sure to be mains water nowadays, though traditionally came from any mucky source.

Does the pointing mortar look different on the two houses - different colour, texture of the sand in it? Was each house done by different crews, different days, different supplies?

Nothing says it has to be just one factor causing the problems. And effluorescense on the outside doesn't account for damp inside.