Sealing decking gaps. HELP

Russell Newell · 20 Sep 2020 at 08:56

I have recently built raised decking using scaffolding boards, pine I think, as decking. I wish to use the space underneath for storage but need to seal the gaps first. Can't use a membrane due to the support beams being below the board level. Have used silicone but can't paint over it effectively and wood filler just cracks. The gaps vary from 2mm to around 5mm. Any advice greatly appreciated.

mickyflinn · 20 Sep 2020 at 09:30

Think you wanted the home and garden section of the forum, hopefully a moderator will move this.

@Space Monkey @ScottiB

Space Monkey · 20 Sep 2020 at 10:07

mickyflinn said:
Think you wanted the home and garden section of the forum, hopefully a moderator will move this.

@Space Monkey @ScottiB

200sols · 20 Sep 2020 at 12:29

You'll never fill the gaps, wood moves and will crack any filler you try and put in.

Abyss · 20 Sep 2020 at 15:53

Short answer is you can't / shouldn't and whatever you do will just leak and cause water to pond on the decking and cause it to rot and algae growth.

If you really do want it waterproof you need to lift all the decking, install a new base similar to a flat roof (Eg two layers of ply overlapped with a membrane on top or similar), then put the deck boards back down. You'd still have issues with the boards sitting in water and rotting though.

SpeedFreak · 20 Sep 2020 at 16:31

As above, terrible idea unless this was planned out from the beginning.