Flat roof leak, caused by moss?

[Morrisman]

Yesterday we had torrential rain here in the Midlands, lasted probably 12 hours without a break. Roads flooded where alive never seen a flood before. This morning I spotted the dreaded puddle of water in the middle of the side garage.

I've just been up on the roof and removed 3 full buckets of loose moss, and noticed loads of bare white spots on the tiled part of my roof, where moss once thrived. Did it drown yesterday and wash down to pile up and cause a flood?

Normally it's stuck like the proverbial to a blanket.



Might be time for a new roof.

The felt itself looks fairly solid, so I can only imagine it overflowed whatever is going on under the part hidden by roof tiles.

This was after I'd removed the bulk of it. There also seems to be a 1/2" or more of 'sludge' underneath it.

 

[gaz1]

sorry to say but your roof has failed

theres no way it can dam up and flood back enough as theres enough slope on that felted roof for it to go off

your slates seem to be the overhanging type of roof like next doors

so if its the roof to garage roof thats failed thats a good point of reference for its failure and to correct this you want built up sides and also edges with torch on or you go down the grp route same method ro get a good corner seal

@roofman will probably say the same as your seal to garage dosnt look good enough

 

[frank horton]

I'd be using steel sheets as a replacement....won't need anymore fall, if it's a nightmare to change......
as long as there is some kind of ventilation for a year or so just put on the original roof with battons and some secure fixings...........

 

[Morrisman]

sorry to say but your roof has failed

theres no way it can dam up and flood back enough as theres enough slope on that felted roof for it to go off

your slates seem to be the overhanging type of roof like next doors

so if its the roof to garage roof thats failed thats a good point of reference for its failure and to correct this you want built up sides and also edges with torch on or you go down the grp route same method ro get a good corner seal

@roofman will probably say the same as your seal to garage dosnt look good enough

I saw some pics of the neighbours roof being replaced and the felt roof seemed to go right across to the house wall, and I assume has a raised edge there. There was 2" of piled up moss along the area of the edge where the tiles come down to the felt, which I've since moved.

I'd be using steel sheets as a replacement....won't need anymore fall, if it's a nightmare to change......
as long as there is some kind of ventilation for a year or so just put on the original roof with battons and some secure fixings...........

Flat sheet or corrugated?
Its never leaked before, so hoping it was just this horrendous rain that was the issue.

 

[gaz1]

I saw some pics of the neighbours roof being replaced and the felt roof seemed to go right across to the house wall, and I assume has a raised edge there. There was 2" of piled up moss along the area of the edge where the tiles come down to the felt, which I've since moved.


Flat sheet or corrugated?
Its never leaked before, so hoping it was just this horrendous rain that was the issue.

it would have to be a flat roof corrugated would be very difficult to seal from one roof to another

as goes for your first comment not every roof has that raised edge or have it done properly yes it will have been frozen and cracked at that corner so any blow back will go in at that point
the corner also makes me wonder if they have also done the same where the plastic ridgeboard is both points are the weak points on a flat roof thats why dormer roofs fail often at the rear of them

its not your slate roof that looks fine from your pics and moss wont cause it either unless it lifts a tile

 

[addjunkie]

it would have to be a flat roof corrugated would be very difficult to seal from one roof to another



its not your slate roof that looks fine from your pics and moss wont cause it either unless it lifts a tile

its not often I agree with Gaz but think hes right in this case.

 

[Barking Mat]

Flat roofs, they're going to leak.

 

[Screwdriver]

I sprinkle bicarbonate of soda on my felt roof. Kills moss and lichen.

 

[addjunkie]

I sprinkle bicarbonate of soda on my felt roof. Kills moss and lichen.

Jays fluid does too.

 

[8ob]

Walking about on a flat roof covered in pea shingle isn't a good idea.

Bob

 

[roofman]

Walking about on a flat roof covered in pea shingle isn't a good idea.

Bob

Does no damage whatsoever Bob..think of a bed of nails spread load,same principle. Any flat felt roof lasts twice as long if it has stone or gravel as its UV protection and if its covered with nice damp moss then even better. The only aging process with felt roofs is UV damage.

 

[Morrisman]

I knew what the result would be, and last night I kept an eye on it, more torrential rain, and there was some seepage.

It starts against the house wall, then drips from the edge of the ceiling sheet in the centre of the garage. There's a 3/8" drop across that 1 metre, so it's running along once it builds up.

That must mean the leak is towards the house side of the roof, under the tile area I assume, but I've just been up top again and there's nothing obvious to see.

Years ago I would have seen this as an opportunity to may e extend and improve the garage...... but the enthuse has long gone, along with the finances for such fun.

 

[gaz1]

the leak is from the outside wall to the overhang of the roof where the seal has broken

just like i said

 

[mcostello]

Moss will indeed make a horrondus leak, especially if a racoon rips off 1 square foot of roofing eating what ever bugs live there. The only thing that stopped it was the roof was layered with boards from a long time ago.

 

[pedrobedro]

Moss will indeed make a horrondus leak, especially if a racoon rips off 1 square foot of roofing eating what ever bugs live there. The only thing that stopped it was the roof was layered with boards from a long time ago.

Luckily we don't get many racoons hereabouts

 

[mcostello]

You don't have them? Lucky You are!

 

[Morrisman]

Meant to update this before, but unseasonably dry weather and Xmas etc got in the way. A gentleman known here as @roofman offered to come round and have a look, gratis. I sort of expected much sucking of air across teeth, and very worried expressions, but t'was not to be.

15 minutes up on the roof and all was revealed. The moss growing on the roof tiles was blocking the built in drainage grooves in each tile, where they overlap. Tiles were swiftly slid back, much to my surprise, I had no idea that could be done, and it was obvious exactly where water was getting under the tiles and running down the lining, membrane, whatever it's called, and leaking through before the edge of the garage roof proper, and running down the joist.

I've since been up and scraped a whole bunch of moss out between the tiles on that side of the roof, and despite torrential rain occasionally, no more leaks.

I love this forum.

And many thanks to Roofman.

 

[roofman]

Meant to update this before, but unseasonably dry weather and Xmas etc got in the way. A gentleman known here as @roofman offered to come round and have a look, gratis. I sort of expected much sucking of air across teeth, and very worried expressions, but t'was not to be.

15 minutes up on the roof and all was revealed. The moss growing on the roof tiles was blocking the built in drainage grooves in each tile, where they overlap. Tiles were swiftly slid back, much to my surprise, I had no idea that could be done, and it was obvious exactly where water was getting under the tiles and running down the lining, membrane, whatever it's called, and leaking through before the edge of the garage roof proper, and running down the joist.

I've since been up and scraped a whole bunch of moss out between the tiles on that side of the roof, and despite torrential rain occasionally, no more leaks.

I love this forum.

And many thanks to Roofman.

Glad you sorted it, i had leave handy to be in birmingham the same day otherwise i would of done it for you or at least with you

 

[Onoff]

Roof problems? I've got two!

https://flic.kr/p/2gkrH36

Hopefully I'll get this sorted this year if I get planning permission

Little video:

https://flic.kr/p/2jbfMgx

 

[gaz1]

yours is easy if you grp it

but depends on your boards if they are rotten or not but if they are put slopers on the roof first and then put new boards on top of them and just grp it like the above video

and no planning permission is needed