Shed Floor

[MG David]

My garage's role as a workshop is increasingly compromised by the other clutter that is in there such a lawn mowers, bbq, bicycles etc. So I am building a lean to shed against one end of the house.

At the house end the floor joists will sit on a length of angle iron fixed to the house. At their other ends they will sit on a concreate/brick foundation sticking proud of the ground. The joists will be 1.7m long.

I was thinking of using 50mm x 100mm joists but would 50 x 75 be good enough?
What spacing should I go for?
The floor will be either t&g, 13mm ply or OSB. Any comments on these and how they effect the joist choice would be welcome.

I know its not welding but it is stopping me doing any welding at the moment.

Thanks,

David

 

[Shox Dr]

4"x2" (100x50) would need to be spaced at 400centres and supported along their length every 2' (600), as yours are only 1700 long I would say a single pier in the middle would suffice

 

[pedrobedro]

At 1.7m (5ft) long your choices would both do the job if you are just putting your lawnmowers and junk in there. Go with a bit thicker floor like 19mm OSB and they will be fine at 600 centres with no support in the middle. It's a storage shed not a high traffic area isn't it ?

 

[MG David]

Yes it is just storage. The garage is the workshop.

The shed walls will be either shiplap or feather edge. Any ideas on the size of timber and spacing for framing the walls? I had wondered about 50 x 75 but would 50x50 do? The roof will be 13mm OSB with felt on it so not very heavy.

 

[Bigjoe]

I would use 3x2" for the wall framing on 16" centers, and the floor will be fine in 4x2" with osb/ply over the top.

 

[SC_BK]

Use second hand scaffold boards for the floor, thats what I did on a recent shed extension. Very cheap and very strong

 

[Shox Dr]

At 1.7m (5ft) long your choices would both do the job if you are just putting your lawnmowers and junk in there. Go with a bit thicker floor like 19mm OSB and they will be fine at 600 centres with no support in the middle. It's a storage shed not a high traffic area isn't it ?

1.7m unsupported is a big gap. It's a damn sight easier to put a small pier wall in the middle while building than have the floor sag. People don't realise how many stuff weighs when piled on top of each other

At the very least stick a joist in the middle and bed it on some motar

 

[Neilios]

1.7m unsupported is a big gap. It's a damn sight easier to put a small pier wall in the middle while building than have the floor sag. People don't realise how many stuff weighs when piled on top of each other

At the very least stick a joist in the middle and bed it on some motar

Agreed.

 

[mjsroofing]

best to make it well now , or you could end up with a total rebuild in 6 months,

4 by 2 floor joist min i'd say with noggins and a 19mm osb boards finish, dont go lower than 4 by 2 m8 it wont take it., i got 6 by 2's over my unit's office with a span of 2m and that moves with the storage above,

 

[steeo]

Use second hand scaffold boards for the floor, thats what I did on a recent shed extension. Very cheap and very strong

Good idea as they won't sag over 5'. When they are been used with scaffold they are used with an 8' span up sometimes 200' in the air so sagging would be a big no-no.

 

[Shox Dr]

Good idea as they won't sag over 5'. When they are been used with scaffold they are used with an 8' span up sometimes 200' in the air so sagging would be a big no-no.

I hope not. Even Youngman's need better support than that

That all depends on the type of Board, there is a scaffold system called Kwikstage (Im using some at the mo) that is design to take an unsupported 8" board. The boards are thicker than your std been 2"+, any other type of board must be supported at least every 4'. Might even be a meter these days.

 

[brightspark]

a 50mm board has to be suported every 2.6meters thats for light inspection work only .heavy working conditions are a shorter spacing

 

[pidgeon chit welder]

One of my lean to sheds 5 mtr x 3 mtr had second hand paving slabs laid on 6 " of lean mixed dry mixed ballast combined with a 12 to 1 portland dry .All tamped flatand eventually dry grouted in the 10 mm joints ( used bits of 10 mm thin wood to set the spacings right ) , corners , mid point and door frames were "H " section 9 foot concrete posts set in 750 mm holes set on concreted bottoms. Clad the posts on the H insets 2x3 ( ish) rough cut batons studding bolted through in through the grove and fastened with nylocks and penny washers .
Upright battons a fixed at both ends to the house wall on chem -studding above the DPC .

Roof was twinwall polycarb and correct roof bars etc ( best thing I ever did as there were no windows in the walls ). I clad it in shiplap glued on with external grip adhesive and 30 mm zinc clout nails then fitted a proper gutter system .
Made both the doors... one at either end, hinged on the same side to allow either end access at 1.1 mtr wide on a 40 x 30 mm pine frame that had reinforcing braces in it as well as a very big over sized thick block for the lock so there was plenty of " meat " to play with when putting on the outside security plate , used weather proof 5 mm balanced ply either side as the skins , these were also put on with 20 mm zinc clout nails and industrial external use adhesive .


All screws on the outside were security ones on the three T heavy duty hinges on each door , they also had several coachbolts and penny washes on the inside to reduce the ease of then being jemmied off....you have to put reinforcer strips in to suit your hinge arrangement so you actually fix through the reinforced part rather than just fix through two thickneses of thin ply . . I used mortice 5 lever locks behind reinforced plates and 5 mm thick home made mild steel recessed keeper plates .

My floor cost me about £50 in the slabs and the same in ballast and cement powder . Concrete slab floors do not rot nor do concrete upright posts rot as quick as wooden ones.

I put a 4 x4 inch rough cut collar plate on the roof lower wall top ..had to add some thick noggins using glue and screws to the wooden uprights to screw it down onto the upright concrete posts .

I did have to dig out the floor to get the finished floor top 9 inches below the house dampcourse , the wooden uprights fastened against the house were also a few mm above the dpc to stop rising damp.

The high roof plate was 50 x 75 rough cut was pre drilled and then fitted over level end studding lengths that was chemically anchored to the house wall , the inside anchors were then put in place ... expanding anchor bolts and screws are not the best of fixings for screws rust , they are difficult to retighten should the need arise and expanding anchor bolts break bricks and mortar .

I used big penny washers and nylock nuts on the wood face to fix the plate securely once all the anchors were fully cured

All my wood came from a timber merchants ..as it was far cheaper than B&Q type places.
The roof came from a specialist UPVC roof wholesaler who calculated the complete shebang needed bars plates and end caps etc. from my buildings external dimensions it came in at £ 285 .


All my ironmongery came from Screwfix as it turned out to be the cheapest place around
I also purchased a fine toothed tennon saw to cut the ploycarb and a roll of the " sticks to anything " lead coloured plastic film falshing to seal the roof to the house wall to keep things totally dry should the rain hit the house wall and run down it on to the roof.

Once the shed was completed I sprayed 5 ltrs of clear Cuprinol wood preserver twice on all the inside wood surfaces and cut ends and one spray on the outside.

Looking back my decison to use the slabs and clear roof was a fantastic benefit long term as it also added about £2400 to the house value once it was painted with a couple of coats of Wimbledon wall green so it matched the perimeter fences .

I was also able to use it as a growing house to get my plants started , I ran out three protected switched 2 gang sockets as well for the propagator and a light system etc..

I also used the " shed " as a woodwork shop as the light was good in almost all weathers.

 

[cazl1994]

Good idea as they won't sag over 5'. When they are been used with scaffold they are used with an 8' span up sometimes 200' in the air so sagging would be a big no-no.

they still sag when supported at about 4 foot on the scaffold with some weight o them so you still need joists
4x2 is a bit small we have 7x3 in the loft of our shed witth a span of about 2m and osb on the top dosent move an inch better over enggineer it then have it sagging after a few months

 

[MG David]

Pidgeon, thanks for your long post. Having slept on the matter I leaning towards a solid floor as well. An air gap, the depth of the joist plus the floor was starting to give more of a step into the shed than I want.

 

[pedrobedro]

I hope not. Even Youngman's need better support than that

That all depends on the type of Board, there is a scaffold system called Kwikstage (Im using some at the mo) that is design to take an unsupported 8" board. The boards are thicker than your std been 2"+, any other type of board must be supported at least every 4'. Might even be a meter these days.

We're getting carried away here, he's not 40' up with a hod full of bricks on his shoulder he just wants to keep the lawnmower and a couple of bikes dry and will probably only go in it once or twice a week.

 

[steeo]

We're getting carried away here, he's not 40' up with a hod full of bricks on his shoulder he just wants to keep the lawnmower and a couple of bikes dry and will probably only go in it once or twice a week.

That is why I agreed with SC_BK on the scaffold boards, you can pick them up second-hand for next to nothing and they are thick enough to do the job without the need for centre supports over the 1.7m span.

 

[SC_BK]

As above you get "thick" and "thin" scaffold boards. 50mm and 38mm I think they are? Both types are 230mm wide

As standard, the thin ones are 13/14ft long and need supported every 1.2-1.4m.
The thick ones are 8ft and only need supported only at the ends.
That is for commercial use as scaffolding, halfway up a building with loads of weight on top. Bare in mind used boards are sold off cheap for a reason, they've lost some of their strength.

So the thicker ones are stronger but obivously mean more of a step up.

My shed extension floor is made from used 13ft (thin) boards. It's 8ft by 8ft and is supported by 4 lengths of 3x2 running parraell, evenly spaced out. The floor is pretty bombproof! I also made a workbench out of the scaff boards and 3x2s which is equally strong.



New scaff boards cost about a tenner, and I was paying £2 for the used ones

 

[Douglas]

I have some 'yellow peril' scaffolding. The boards are around 60 mm thick (that's a guess, it's dark and wet outside) and they are eight feet long and I can fully bump them out with bricks, mortar, tools and self with no flex at all even when splitting bricks with a bolster. I would be more than confident to use them as a storage shed floor at the length you mention with no joists at all. Hire companies flog them off cheaply when they're past their best or have paid for themselves; that's how I bought mine.
Might be a cheap option.
Regards.

 

[MG David]

I have just finished the shed. In the end I used a solid concrete floor laid on top of a plastic sheet DPM.

The roof is made from twin wall polycarbonate sheet. This has made it very light inside. It has already been called the giant coldframe.

How long should I leave the concrete before I paint it with floor paint?