Manhole cover trays.

[Gilesda]

Hi all.
I've laid a porcelain patio and just have the drain trays to fill in. They are 45mm deep and about 680 x 540.

I want to keep the weight of them down and with 25mm of concrete then the 20mm slab I think that will be too heavy

I was thinking of putting in insulated tile backer board 20mm thick, which is very light and dense, then the slab over the top. That gives me 5mm to adhere the foam board to the metal tray and the porcelain slab onto the board.

I thought about silicone, a lot of it, on each surface. Is there anything else I could possibly use if silicone sealant isn't a good idea?
Thanks for any help.

 

[Ivor Windybottom]

Good idea. I have the same situation, haven't got round to filling mine yet. They're designed for block paving, so they're really deep. But blocks are normally put in loose so can be removed in future.

Silicone will be a bit springy, which would mean that the tile grouting would crack away from the edges of the tray.

Are they metal or plastic trays? Silicone doesn't stick at all well to some plastics, it basically shrugs off.

I'd suggest a solvent based glue, which will set hard rather than rubbery. Something like this...

https://www.screwfix.com/p/everbuild-solvented-grab-adhesive-pink-350ml/6048h

But check compatibility with the exact type of plastic the tray is made from. Other glues may be better.

There should be some tiny drain holes. Don't block them, put the glue on in blobs or lines so any water can drain into them. If it's plastic then drill some more holes. Don't drill into galvanised metal, they'll rust if you do.

 

[jj4091]

Could I advise you to put plenty of grease on the underside no matter how much weight you have in them as they rust in place in rhe frame and you can't get them up without damageing the surface

 

[noseall]

Could I advise you to put plenty of grease on the underside no matter how much weight you have in them as they rust in place in rhe frame and you can't get them up without damageing the surface

I don't think I've lifted one yet where we haven't had to remove the paving first. I've even lubed one and still ended up removing the blocks.

 

[HERTS P&D]

Use a manhole cover with eyelets, very easy to lift with no damage when using a manhole lifter.

Recessed Manhole Cover 600x450x80 – Advanced Resin Supplies

www.advancedresinsupplies.co.uk

Andy

 

[jj4091]

I don't think I've lifted one yet where we haven't had to remove the paving first. I've even lubed one and still ended up removing the blocks.

Ours was done with imprinted concrete so could not empty it.

Use a manhole cover with eyelets, very easy to lift with no damage when using a manhole lifter.

Recessed Manhole Cover 600x450x80 – Advanced Resin Supplies

www.advancedresinsupplies.co.uk

View attachment 423719

Andy

It was impossible with ours because it had rusted in so firmly.

 

[HERTS P&D]

Sometimes i will cut around the joint between the manhole and frame with a thin angle grinder blade.

Andy

 

[Gilesda]

Thanks for the replies everyone.
The covers I've got are Clark recessed like in the picture. The frame is plastic so I shouldn't have a problem with them rusting in, I'll still put grease around the rubber seal though, incase that sticks to the galv. That was a good idea from jj4091, especially if you've got all metal covers.

I think I'll do what Ivor said, use a solvent grab adhesive and see what happens. If anything goes wrong in a few years time I'll rethink and redo it.

I was going to use silicone because I can get it for free. I'm a sheet metal worker and use it on different jobs. I used to make stainless steel serveries for restaurants. Some of them had hot plates on the counter top and were usually tiled over. Silicone was used to stick the tiles to the metal plates that were heated by heating elements underneath them. They never failed but epoxy grout was used which I won't be using.

Anyway thanks again for the help. I'll update the thread when I've done it and say what it's come out like and how solid it feels.

 

[Ivor Windybottom]

I've got similar ones, also Clarke. Mine aren't a metal inner as shown above but all black plastic. But it looks like the handles are the same.

I avoided metal deliberately, but I'm not reassured by the plastic handles, I really can't imagine them being strong enough to lift them when full of stone/mortar. I may look into lighter weight options too, but I'll probably just fill them with paving and hope for the best. I'm using slabs, so the amount I'd save by putting something lighter in would be trivial. But for tiles it's more worthwhile looking at.