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Damp proofing my shed


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i'm currently in the process of erecting a small 6x6 wooden shed (pent roof) and have decided to use a simple gravel base to alleviate the need for lots of concrete. I'm not using the shed as an observatory just to store my kit in there.

I have used wooden sleepers to raise and level the ground level and have filled the frame (10'x10') with about 6" of gravel. I plan to simply lay the shed base on this gravel and think it will provide enough support and drainage to not cause many problems with such a small shed.

Im having thoughts about laying a sheet of polythene down before i lay the base however, im not sure if this will help keep the damp out of the shed or trap damp IN the shed. I dont want water collecting under the bearers. The gravel will provide sufficent drainage but how do i stop damp from rising?

I'de like to keep my books and papers in the shed too, but im not sure i can keep it dry enough for this. I was thinking of some membrane on the walls, maybe polystyrene too, and then plywood on top of that.

Any advice would be greatfully recieved


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Heres my two penneth

Firstly, I shouldn't think you will get rising damp through gravel.

Make sure the gravel bed can drain properly to the left where

your raised veggy bed is.

I like to have sheds floating above ground on bearers and my idea

would be to lay another length of railway sleeper along the left side of the

greenhouse level with the left side of the gravel bed and put say four 3"*3"

fence post as bearers across the gap to then stand the shed on.

Plenty of drying air underneath and no rising damp.

As for an inside lining, I did my son's shed with some aluminium foil and foam sandwich

stuff used for putting under plank flooring, stapled to the shed walls.

Got it from B&Q and it works very well as an insulator.

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Hi Gordon,

Be careful here... its very easy to make the shed sweat esp in Summer!!... let it breath thats the best bet. My Kit lives in a very hole riddun shed and is quite happy in there.



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As both Geppetto & Rob have said ,air circulation is a must under your shed,but don't make it a haven for mice to nest under,believe me these little critter's will cause more damage in your shed than a small amount of moisture.

I have found that once the shed is in place,you can get galvanized mesh in 6"x3metre rolls to tack around the base,still allowing air circulating, but deterring the mice!

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Both my sheds have floors, which are fairly easy to make, using a 2"x4" frame and 1/2" plywood. You could put a square of linoleum on it, if you wish. Both sheds are adequately ventilated under the eaves, and I kept a set of the Popular Mechanics Encyclopedia in one for about 10 years without damage. The drainage you have provided with the gravel bed will protect the floor and walls from damage for quite a while.

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Well my shed was delivered today. Didn't take too long to put up at all. I'm quite pleased with the result. I went with just a standard shed in the end, intending to just store my kit in there. I made sure i went with the pent roof design though so that in the future if i want it's easy to take off and convert. I put down treated timber bearers to stop damp and the whole thing sits on gravel about 6" deep so drainage shouldn't be a problem. I also thought that if i get around to putting a pier in there the gravel is easer to move once i've cut a hole in the floor.

Nothing too exciting, but even so, it's one of my more expensive purchases for this hobby!






I've yet to line it and put down a stronger floor of hard board, but those can wait. Of course, being an astro purchase the clouds are here for the next few days, at least i get to test if it's weather proof!

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Nice one Gordon.

I Think I'd put one lock on the gate,& the other two on the shed.

You ca get magnetic screech alarms also.Before you store expensive astro gear,I would check your insurance pollicy,small print in particular. :shock:

If they can get round not paying up they will do. :nono:


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You can get insulating foam thats used in the roofs of houses from a builders merchant, its dead easy to cut and if you keep a air gap between the roof and walls sweating shouldnt be a prob, you can go over the insulation with hardboard afterwards and paint it if you wish


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  • 4 weeks later...

I've superglued the screw heads when i installed it, but i've yet to get around to any REAL security. My mind is if someone wants to steal my stuff you can't really stop them. You can however stop opertunists and i have padlocks on all my gates and on my shed. If they stole my equipment they would have to lift it over my 6 foot fence (i can barely lift it onto my deck!)

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Nice shed Gordon....

Just a thought...Have you put power down to the shed!! For tea and the beer fridge!

You can get those moisture absorbing crystals from B&Q I use them in my porch and caravan...You only need to use them in the colder months!

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At the moment im just running a 15 meter extention cable down there when i need it for my laptop, but the plan is to put an armoured cable to it permantly in the future. More digging though! At the moment im still gathering ideas about my roof. The casters idea is perculating nicely and im thunking of wooden frames come pergolas for roof rail support

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  • 5 months later...

Finally got around to getting electricity to my shed!

I have ran a cable to a fused socket in my Utility room through a hole in the wall (the missus nearly feinted!) which in turn runs to a fuse board in my shed (just in case).

I have installed a 2kw fan heater which i leave set to "frost" and this small heat is enough to keep the dew off.

The extractor fan is a good idea and one I'll look into. I was going to use a 100 watt lamp as a heater but found it wasn't enough to make any difference. I've therefore swapped out to a 11 watt energy saving lamp to make sure theres less load on my cable.

I also planned on adding a red lamp but don't want a queue of dirty old men outside my house so am thinking about a dimmer switch on the white lamp instead.

I've yet to line the walls but polystyrene is the favorite at the moment. Although that being said, the fan heater is working so well I may just leave it unlined.

Oh and i plan on using a timer, one of the old mechanical ones that have pins you move around a dial. I plan on taking out all the "on" pins and only leaving in the "off" pins set at every 3 hours or so. This means I can "turn the shed on" and know that no matter what i do it will turn itself off again in 3 hours (more than enough for one of my sessions)

The roll off is still on the back burner as i'm using a dob at the moment, but an imaging rig is slowly forming in my head so the roll off might come back to haunt me hehe

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  • 2 years later...

Damp Proofing - Duracoat offers a complete repair and decorative exterior coating system which gives a life long protective surface, thereby weatherproofing the structure of your home. The exterior coating system will completely reface your home's exterior walls regardless of surface condition allowing your house to breathe, so no more worries about damp walls, peeling paint, mould or bleaching. You will never need to paint again with Duracoat Systems UK Ltd.

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