New workshop question

[themack]

Hi all

I am getting a new workshop ! I have a small heated workshop attached to the garage, but it houses airbrush stuff, modelling and electronics. All other things like routing, sawing and anything making mess I did outside in a type of lean to porch where I had to cart my saws to. Now I have been given a 10x8 shed as a present for all woodworking stuff. I will have machinery in it and a MFT table. It will be unheated and I have a concrete base down the garden of that size already. It was laid years ago. Here is the shed...
https://www.forestgarden.co.uk/product/forest-10x8-4life-overlap-apex-shed-double-door/
I am planning to seal the shed with silicone where the panels are connnected, I will also put a membrane underneath the roof felt and fit guttering to both sides . However, I am now not sure if the concrete slab had a damp proof membrane added, I presume not. Now i am wondering if the timberframe the shed sits on will soak up moisture from the concrete slab and transfer it to the floor? Would it help to put a membrane underneath the floor frame? It's no good spending all the effort sealing the lot if the damp rises up from the bottom.
Any advice and experiences? Thanks for your help.

 

[MarkAW]

What do you hope to achieve by sealing the panels with silicone?
I have some old DPC and some treated bearers I sat mine on. No rising damp problems.
You may want to think about keeping your tools in airtight containers/toolboxes, or bringing indoors, or keeping them oiled, as with an uninsulated shed you'll find condensation is a problem (happens to metal tools just as it does the grass) in certain weathers.
The gutter will help a lot in keeping the walls dry

 

[themack]

What do you hope to achieve by sealing the panels with silicone?
I have some old DPC and some treated bearers I sat mine on. No rising damp problems.
You may want to think about keeping your tools in airtight containers/toolboxes, or bringing indoors, or keeping them oiled, as with an uninsulated shed you'll find condensation is a problem (happens to metal tools just as it does the grass) in certain weathers.
The gutter will help a lot in keeping the walls dry

Thanks Mark
I just thought that when the frame the shed sits on is in contact with the wet concrete it would "soak up" the water and give it to the floor which is srewed on that frame? So I wondered if I should put a membrane underneath and fold it up the sides of base frame. The silicone would just be where the panels are screwed together and onto floor. Just weighing up before building it.
I wouldn't store the main tools in that shed as I have another small workshop which is heated, only machinery would be in there which I would oil and cover with sheets after use in winter.

 

[flying haggis]

I put dpc under the bearers but only fixed at the ends so no holes for water to get through when I built my shed. Seems to have worked... Make sure you have airflow under as well. I also used stainless steel mesh across the gaps between the bearers and along the two outer most bearers to keep out unwanted guests.
This sort of stuff
https://www.screwfix.com/p/sabrefix-brick-reinforcing-coil-galvanised-dx275-20m-x-112mm/69577

 

[MarkAW]

Yeah putting something waterproof between the concrete and wood would be beneficial. Damp proof course is handy because it's long and narrow just like the timbers. You don't need to cover the entire area, just the contact points.
I'm not sure that sealing the panels will gain you anything, except make it slightly more difficult to disassemble if ever you need to, if done at the bottom I believe it's more likely to reduce drainage/airflow and slow down the drying process, thus increasing chance of rot.

 

[Terry - Somerset]

Is it worth putting some holes in the floor a la soffit vents (one pair for each bearer gap) to ensure a decent airflow which would minimise damp problems anyway.

 

[flying haggis]

Don't think holes in the floor would make a difference. The main thing is to ensure air can flow between the slab and the floor and as others have said dpc under the bearers to stop the wood being in direct contact is good.

 

[Cabinetman]

Silicon sealant between the panels, presumably this is to stop any draughts, I think it would be less messy and easier to dismantle if you were to use rubber draught strip. Enjoy your new space.
Ian

 

[themack]

Thank you all!
I think, I'll just put DPC strips under the bearers as several suggested. The mesh suggested by flying haggis is a really good idea too. I'll fix that around it to keep unwanted visitors at bay . The silicone was to stop draughts and keeping creepy crawlies at bay as I am not good with spiders. I will never dismantle the shed as I am not moving anymore, but rubber strips is an interesting idea, less messy.

 

[themack]

Ohhh, now I just found that !
https://shedbasekits.com/product-category/ecobearer/

 

[MarkAW]

They look good, but a lot more expensive than a small roll of DPC

 

[flying haggis]

why do they only accept timber up to 35mm wide? break the silly lugs of and you could fit wider timber. it even looks like it would take 50mm without taking the lugs off!
and as mark says dpc is cheap as chips, ie roll of this split down the middle to give two strips 56mm wide.
https://www.toolstation.com/damp-proof-course/p27518