Preformed Concrete Guttering

[PTH]

I have a persistant problem with leakage from precast concrete guttering. The gutter sections are about 30" long and effectively form the wallplate that the roof trusses bear onto. I think that the gutter was originally lined with a rubber solution which has long since peeled away. Some but not all of the joints between sections leak, I suspect some of the leakage is finding it's way into the wall cavity.

I've tried using a paint-on rubbber/polymer solution, fibreglass resin and even car underseal (which was the most successful) but I would like to find a permenant solution. My thoughts are as follows:

1 Completely clear out all the old linings, acid etch the concrete surface and apply some sort of sealant directly.

2 Lay in some rectangular section pvc guttering, bedded onto a weak mortar mix - I know this sounds like a favourable option but I suspect that I will have problems where the SVP penetrates and where the downpipe connections are.

3 Lift the bottom row of tiles, put some petrol in the Stihl saw, cut the guttering off flush with the brickwork and fit a facia board to cover the sawn edge, then new plastic stuff.

Has anyone tried any of the above or willing to offer an opinion?

 

[breezer]

why not change it all to plastic guttering?

 

[PTH]

Thanks Breezer, that's my option 3 - I will need to saw off the old stuff as each of the concrete sections is integral with the cavity closure and wall plate which the roof trusses rest on. I was hoping to find a way of sealing the existing channel. I've found a Dow Corning product which may do the job. I'll report back.

 

[david and julie]

Could they be lined with butyl rubber bonded in?

 

[PTH]

Mmm, pond liner or maybe even DPM. Good idea D&J. Thanks for that one - it's now 'Option 4' - I'll look into it

 

[masona]

Why not use lead flashing ?

 

[breezer]

trouble with "pond liner" is it does not like uv light as it turns into "large cornflakes"

that said you could try butyl rubber pond liner, as it is supposed to last 30 years (but that is only if it is used as a pond liner), but pond liners are always under water

 

[PTH]

Masona, thanks. - I did consider lead but as it's a gutter the fall is very shallow (1:100 ish) and I would need very large overlaps or welded joints. The other drawback is that this a bungalow, so quite a large footprint and long runs of guttering. Given the speed that I work with lead, I may finish the job by about 2020, unless I die of injuries sustained from carrying a million tons of code 4 up a ladder.

Breezer - would I need full cream milk for these cornflakes or would semi-skimmed do, also how much should I expect to pay for a bowl big enough for hte whole lot in one sitting.

Seriously though, thanks for that - I seem to remember seeing some pond pond liner advertised as UV stable, perhaps a butyl/nitrile sandwich (oops there goes my food obsession again) I'll do some googling.

 

[masona]

Not sure of your layout, is this any good ?

 

[PTH]

Masona, I owe you a pint, it looks like just the job, in fact one of the pictures appears to show exactly the same arrangement that I'm burdened with. I'll get a sketch off to them for a quote.

Thanks very much to all for the effort on my behalf , I'll report on progress.