Flood proofing new shed

[glenfield2]

A year ago much of our village flooded in Storm Babet. We were 16ins in deep in he house and the garden shed at the end of our sloping site nearly 3ft under!

I want to build a replacement - it’s a shed, tool store, bike store etc. How can I mitigate flood damage. Hopefully we won’t get another Babet but who knows.

It will be a timber shed. I could raise it off the ground on ground screws maybe but realistically only 9-12 ins. I can keep vulnerable stuff hung up etc. Any thoughts on how to make the structure itself more water resistant?

 

[Fitzroy]

Beware making it watertight will create a boat, a 4mx4m shed in 1m of water will need to weigh more than 16tonnes before it doesn’t float!

Raising off floor and storing stuff up high sound very sensible, also not using absorbing insulation or glass wool, and having the base ventilated underneath to aid drying.

 

[dzj]

Make it buoyant. A shed/ raft.

 

[Pedronicus]

Perhaps you need to build it on something like those concrete mushrooms that farmers used to install to prevent vermin getting into the barns/grain store!

 

[Orraloon]

The sad truth is any place that has flooded will be prone to doing it again at some time. Climate change making those floods more frequent. Site it as far up the block as you can and build it up on legs as tall as allowed. At the very least aim for the floor being above the peak of the last flood.
Regards
John
PS
This kind of thing but with the floor as high as needs be.
DIY Pole Barn Shed from Start to Finish - YouTube
.

 

[niall Y]

The consensus seems to be to build it as high off the ground as possible,

My own workshop has flooded a few times with flash floods, and the basic observations I would make would be to keep your electrics well off the ground and have everything stored in watertight boxes , that is below waist height.

Another approach would be to build in concrete block and waterproof render it and put in a flood barrier across the doorway.

A customer of mine used to have the lower part of his garden flooded on a regular basis. He resorted to having a small, clay embankment/ polder built, which seemed to cure the problem

 

[Amplidyne]

Make it buoyant. A shed/ raft.

Indeed. Make it from ark welded steel.

 

[TRITON]

Legs

You have the shed safe above the water level, plus you can use the space underneath for storage/*** dungeon.

 

[Bingy man]

I’d be building it and or raising it off the ground at least as high as the 3 ft you mention. Anything that doesn’t like to be submerged in water store high as possible . You could even devise a jack system whereby it could be raised up and then lowered when conditions improve. I guess it depends on the weight of the shed and its contents ..

 

[O'Chippy]

Incorporate a pontoon base into the design, much like you'd see in a boat marina.
Cheap and simply to make and very effective.

 

[glenfield2]

I’d be building it and or raising it off the ground at least as high as the 3 ft you mention. Anything that doesn’t like to be submerged in water store high as possible . You could even devise a jack system whereby it could be raised up and then lowered when conditions improve. I guess it depends on the weight of the shed and its contents ..

Two problems with getting it above flood level - permitted development height means that’ll be three feet less headroom inside.
And the missus won’t be too chuffed at having to get the lawnmower up and down a steep ramp!

 

[O'Chippy]

Two problems with getting it above flood level - permitted development height means that’ll be three feet less headroom inside.
And the missus won’t be too chuffed at having to get the lawnmower up and down a steep ramp!

Pontoon design circumnavigates both those issues.

Well it does useless some jobsworths reports the elevated ridge height mid during a flood, or the misses wants to mow the lawn during a flood.
If either of those situations present themselves, I suggest getting into the pontoon shed, slip lines and sail off over the horizon.

 

[Bingy man]

Two problems with getting it above flood level - permitted development height means that’ll be three feet less headroom inside.
And the missus won’t be too chuffed at having to get the lawnmower up and down a steep ramp!

I hear you on permitted development but was thinking of a temporary measure rather than a permanent build during the winter months. And during any severe focast rain

 

[Stanleymonkey]

Sounds like a challenge! Have you made any changes to protect the house - will they impact on the garden water levels / movement of floodwater through the garden?

Did you have time to prepare before the last storm? If you are at home a lot / work locally most of the year then that could be part of your planning.

Would it be more feasible to have grab boxes to move stuff into the house - upstairs / loft if you know a big storm is coming. Light enough to carry, sized to go through doorways and designed to stack in a corner or the bedroom or up in the loft. I would imagine you can build a big slab and incorporate removable barriers into it - but again you would have to be home to install them correctly to protect your stuff.

 

[Spectric]

The obvious choice and one that will also relieve stress is to just move but I dare say selling up would not be easy. Next option is to buy an old barge and use that as a shed.

 

[Orraloon]

Some years ago I visited Vietnam where flooding is a regular seasonal event. The ground floor of most buildings is concrete with tiled floor and walls. After each flood they just sweep out the mud, hose things down and get on with life.
Regards
John

 

[Mike Needs Help]

You could fibreglass the inside and make an emergency fibreglass panel to screw over the door opening. Obviously you are making a boat so you would need something to stop it floating off, maybe 4 pieces of channel section concreted in at the corners with 4 large castors on the shed to allow it to move up and down?
It might be that the risk is not worth the cost of prevention and you decide to only do the minimum. In any event why not put some ceiling sockets in? I put several in my garage when I converted it to a workshop some years ago and it's great not having cables trailing all over the floor.
I see you are in Suffolk. I'm in Framlingham so we might be able to help each other out from time to time. PM me if you want to get in touch.

Mike

 

[Blister]

Put it on cement columns 2mts tall , when the council ask WT- tell them its flood defences

 

[Blackswanwood]

This must be a problem an increasing number of people are facing.

As I see it there are two choices. Stop the water reaching the shed or put the shed on a base that will rise with the water.

If you cannot build it on stilts could you put a brick or block bund around the shed with a flood gate? Alternatively the bottom meter of the walls could be brick or block built with the flood gate over the door?

If that doesn't work build it over some pontoon tanks or plastic drums that will lift it as the water rises? Either tether it or use a collar and vertical pole to stop it floating away.

When you do work out the answer we'll look out for you on Dragons Den

 

[Duncan A]

Welded steel plates for the floor and sides to above the expected water level. Steps/ramp for access inside and out. Insulated inside. Use high quality marine paints for corrosion protection - it's good enough for ships sailing in salt water. Timber construction above that.
If inside working when the floods arrive, you may need a zipline to have supplies sent over from the house!
Duncan