DIY Flood barrier

Janice555

Hi,

I'm thinking of making my own flood barrier, ie, a sheet of material surrounded by neoprene seal and secured against a door, something like this:

Would anyone have any advice how thick a plywood, or aluminum, or any other better material, should be to protect a 2 meter wide and a 1 meter wide door?

I cant seem to find a decent answer in general. It may be a fool's errand to try and compete with a professional flood barrier but they are really expensive for what is effectively a big sheet of something......

Thanks very much if anyone can advise...

Lumen

At an average depth of 20cm, water pressure will be around 200kg/m2, so a 2mx40cm barrier will only need to take 160kg evenly spread.

I'd probably use 12mm marine ply with a couple of reinforcing battens running lengthways on the back to make it easier to handle.

10-10-20

I'd go bigger than 12mm as you want to avoid flexing around the mid-point. Probably 18mm or 20mm as mentioned.

Additionally, I don't think neoprene will seal that well. Perhaps think about window rubber or the equivalent.

The key thing to get right is the method of tightening it against the rubber. I'd just run a baton up the wall and secure it against this using screws, but that baton also needs to be sealed to the wall. The seal against the ground will be interesting. Maybe pre-drill holes and fit good screw-anchors and then have a removable baton which is fitted with rubber and secured in place as needed.

GreeBo

I think I would go with some 10mm polycarbonate sheets sliding them into some 12mm aluminium c channel fixed to the floor and walls.

to avoid a trip hazard I would recess the c channel into the floor.

When you need to use it you can just silicone it in and then cut it out when you are done.

I dont think you are going to get a watertight seal with anything permanent, unless you can get a wider c channel and fit some expanding foam tape into it, then rely on the water pressure to make a seal.

Janice555

Thanks so much for the suggestions!

I think something like 18mm ply to be safe then, I was thinking polycarbonate but a very nice man at a supplier said he wasn't so sure it'll be strong enough so I knocked that off the material shortlist. 18mm marine ply at 2m x 0.5m is 12kg in weight or so manageable (the lighter weight for easy of fitting the better).

Great advice for sealing too thanks, I'll looking to window rubber and expanding foam, or both, fitted into a c / u channel. If I can arrive on the sheet material (looking like ply) I can really think about going to town on battons/sealing....

Cheers!

GreeBo

Polycarbonate is about 4 times stronger than ply of the same thickness, it also wont warp and swell (which could be a major problem in your use case!)

Its often used as a hurricane protector over windows and in riot shields.

Poly is more flexible than plywood would be, but if you allow for this in your design to ensure than any flex doesnt result in the sheet popping out of the C channel it will be fine. Flexibility also means that it wont be as likely to crack under pressure.

If you still had concerns you can either go thicker or allow for install of a middle post to support the back of the poly sheet, alternatively it can just flex against the door thats behind it!

This looks like maybe 6mm sheet (obviously a smaller span than you have)

https://youtu.be/eXeNE5aVnz4?t=744