# Shed Needs A New Floor



## l008com (Mar 7, 2015)

The floor of my shed is totally rotted. I don't mean just the plywood floor, I mean all of the 2x4 structure under that too. When I purchased this house last year, the back of the shed (the land slopes down) was a few inches off the ground, and the front was on the ground. There were a few bricks under each corner but they sank right in. And they just left it that way. 

So I put proper, solid, heavy duty supports at each corner, and I put two 4x6 under the existing rotted wood so at least the shed would stay up. But now I need to replace the floor so I can start putting all my **** in there.

So here's my plan. I'm thinking I'll attach a 2x8 to the exterior side walls, with plenty of screws that go in to the studs. Then I can jack the shed up BY it's walls. Cut the floor off, and rebuild a new floor right under the shed. Then lower the shed back down on the new floor and I should be good to go. I was going to use 2x6 for the new floor so it will be a little stronger, since it's a 10 x 10 shed. And I was originally thinking of using regular wood, but in this size, PT is only a few cents more per piece than non-PT. 

I'm going to have some specific questions along the way with this, but first I wanted some opinions on the plan as a whole. Someone suggested that I just disassemble the shed, but its too big for me to do solo, and plus having never done anything like that before, I don't think it would ultimately work out. 

I don't have many pictures either, so here are two from different angles. 

Starting Pic:
http://i.imgur.com/62yOkCU.jpg

Leveled and off the ground, but still rotted floor:
http://i.imgur.com/CoTDsjr.jpg


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## Bondo (Dec 8, 2007)

Ayuh,.... No reason yer plan won't work, I've done similar before,.....

PT 2x6s might be overkill, but it oughta last 100 years,....


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## l008com (Mar 7, 2015)

Its like 20¢ less for non-PT, might as well use it. I just double measured up the shed and everything looks good to me. Also turns out the old base IS 2x6 after all. So much of it has rotten (mostly from the front side) that it looks like 2x4. But from the back you can see it's actually 6". 

Also it turns out the studs in the walls and roof are spaced 24" apart. This may not be good for strength but its probably good for me for now, because it makes it even lighter. And augmenting the walls with extra 2x4's should be easy enough once the sheds all back together and solid


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## Homerepairguy (Aug 1, 2010)

l008com said:


> .... since it's a 10 x 10 shed.
> 
> Also turns out the old base IS 2x6 after all. So much of it has rotten (mostly from the front side) that it looks like 2x4. But from the back you can see it's actually 6".
> 
> Also it turns out the studs in the walls and roof are spaced 24" apart. This may not be good for strength but its probably good for me for now, because it makes it even lighter. And augmenting the walls with extra 2x4's should be easy enough once the sheds all back together and solid


For a 10 foot span using 2x6 floor joists 24" apart, recommend using three 4x4 beams to rest the floor joists on top of. This would limit the unsupported span of the floor joists to about 5 feet. I'm speaking from experience. I had a 10 x 12 shed with floor joists spaced 24" apart. I had only supported the sides of the floor joists leaving about 9' of unsupported span. The floor joists sagged in the middle over the course of 20 years.

You could use only two 4x4 beams set in from the side walls about 1.5' so that the unsupported center span would be 7' with 1.5' cantilevered floor on both sides. But for the cost of one more 4x4x10, I would use three beams.

24" apart for rafters and wall studs are fine. My old shed had that and there were zero problems for those.

HRG


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## l008com (Mar 7, 2015)

The current floor is spaced 16", it's the rest that is 24". But I was going to space the new floor at 12" since the wood isn't that expensive and you don't need too many more pieces to put them that close together. As for the 4x6's that they floor joists rest on, I like the simplicity and easy adjustability of having just four ground supports, so I might use some steel stock to add extra support to those two pieces.


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## MT Stringer (Oct 19, 2008)

I have seen this type of repair done several times. A friend had to replace part of his studs and the bottom plates. He jacked up his garage and poured new concrete footings.

My dad did the same thing in the mid 70's. It was a one car garage with dirt floor. He jacked it up, made the repairs and poured a new short concrete wall (8 inches?) all around. As far as I know, the building is still standing.

Edit. My 10x12 building is on 3 or 4 4x4's which sit on concrete blocks. I forgot if I used three or four.

2x6's for the floor joists 16 inches on center. Walls and rafters are 24 inches OC.


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## l008com (Mar 7, 2015)

OK question time. The shed is 10' x 10', what size lumber should I use for the new floor, spaced 12" apart? The old floor is 2" x 6". I was going to use this, but a contractor pal said I should use 2" x 8" at a minimum, but really should use 2" x 10" for the new floor. That seems like super overkill, using 10" floor. The house itself only has 2" x 8", 12"-spaced floor joists and its about 13' from the foundation to the centerbeam of the house.


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## Homerepairguy (Aug 1, 2010)

l008com said:


> OK question time. The shed is 10' x 10', what size lumber should I use for the new floor, spaced 12" apart? The old floor is 2" x 6". I was going to use this, but a contractor pal said I should use 2" x 8" at a minimum, but really should use 2" x 10" for the new floor. That seems like super overkill, using 10" floor. The house itself only has 2" x 8", 12"-spaced floor joists and its about 13' from the foundation to the centerbeam of the house.


For a 10' x 10 foot shed, 2x8 or 2x10 floor joists are way overkill in my opinion.

For a 10' x 10' shed:
If you use 3 support beams, you could use 2x6 floor joists spaced 16" apart for 8', and spaced 12" apart for the remaining 2',and that would be more than sufficient. 

With 3 support beams, the two side beams would be set in about 6". Therefore the span between the two side beams would be 9 feet. Therefore the floor joists would only be spanning 4.5' to the center beam. Use 3/4" plywood for the floor. Everything using treated lumber of course.

If you use 4x4 support beams, assuming that you leave 6" overhang at both ends, that would put the remaining span at 9'. Using 4 posts per beam, that would put the support posts 3' apart. You could use 4x6 support beams if you think they would be better than 4x4 beams.

Be sure to put 2x6 blocking between the floor joists over each support beam.

$.02,
HRG


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## Homerepairguy (Aug 1, 2010)

Homerepairguy said:


> EDIT: In my previous post I said "Be sure to put 2x6 blocking between the floor joists over each support beam."


Change the above to: "Be sure to put 2x6 blocking between floor joists over the center beam."

No blocking is needed over the side beams since the 2x6 header joists on both sides will hold the floor joists vertical at the ends. (The header joists are the ones at the end of the parallel floor joists on both sides.)

HRG


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## l008com (Mar 7, 2015)

So there is no centerbeam. Which I assume is why he wanted 2x10"


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## ron45 (Feb 25, 2014)

Just my opinion....
What you are planning is going to make it difficult to park the riding mower in, not to mention the oversize step.

You already have it above ground, just tear out the existing floor and pour a slab. Make all your repairs to the walls and lower it down.


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## l008com (Mar 7, 2015)

Well, there is no riding mower. And pouring a slab for a shed seems like major overkill.


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## MT Stringer (Oct 19, 2008)

Here is what my shed looks like. I recreated it from memory. I built the shed in 2002. So far, it has withstood two hurricanes, the last of which, came right over us (Ike).

Recently,I replaced the doors with new ones. and the corner trim and fascia are on the list to replace also. Everything else is good to go.

2x6 floor joists 16 inches apart. 3/4 plywood for the floor. No problems.
Hope his helps. 
Mike


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## l008com (Mar 7, 2015)

I don't think I mentioned this yet but my yard is not level at all, it slopes down diagonally across the bottom of the shed. And there's also a lot of rain runoff that can soften up the ground alot. This is why I'm trying to get by with just 4 supports instead of 6 or 9, that way it can be very easy to jack up a corner and add some height to that corner if it sinks in any more over time.


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## Homerepairguy (Aug 1, 2010)

l008com said:


> I don't think I mentioned this yet but my yard is not level at all, it slopes down diagonally across the bottom of the shed. And there's also a lot of rain runoff that can soften up the ground alot. This is why I'm trying to get by with just 4 supports instead of 6 or 9, that way it can be very easy to jack up a corner and add some height to that corner if it sinks in any more over time.


Out of curiosity, how long will the longest support post be and how long will the shortest support post be?


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## l008com (Mar 7, 2015)

Well, it's a 10' by 10' shed, the supports at each corner are 11" by 11", so the gaps for the support beams will be a hair over 8 feet. And the actual floor joists will have 8 or 9 foot gaps depending on exactly how I line things up.


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## Homerepairguy (Aug 1, 2010)

l008com said:


> Well, it's a 10' by 10' shed, the supports at each corner are 11" by 11", so the gaps for the support beams will be a hair over 8 feet. And the actual floor joists will have 8 or 9 foot gaps depending on exactly how I line things up.


Oh, that's why the larger floor joists were recommended (having the floor joists span 9 feet). 

I would install 3 support beams (under the floor joists) so that the floor joist span would only be 4.5 feet (assuming that the floor joists will overhang the side beams by 6" on both sides.) Then you could use 2x6 floor joists.

Personally, I don't think having only 4 posts at the 4 corners so you can jack up the shed easier is a good idea. You would have to have "large" support beams and "large" floor joists. I think laying out the plywood flooring so that the center section is removable, for maintenance of the posts under the center support beam, would be a lot better idea. The outer perimeter of the plywood flooring would not be removable since you will probably have shelves with a lot of junk on them. But you can access the support posts for the two side beams from the outside of the shed for maintenance.

HRG


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## l008com (Mar 7, 2015)

Here is a plan I came up with tonight. The outer dimensions are exactly 10' by 10'. I stuck with 4 supports and there are no support beams. The outer 'box' is 2" x 8" doubled up all around, then all the inner joists are 2" x 6" spaced at 12" and hung with joist hangers.


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## l008com (Mar 7, 2015)

The more I think about it, the more I think maybe I should just do the whole thing in 2x8. I dunno.


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## Homerepairguy (Aug 1, 2010)

l008com said:


> Here is a plan I came up with tonight. The outer dimensions are exactly 10' by 10'. I stuck with 4 supports and there are no support beams. The outer 'box' is 2" x 8" doubled up all around, then all the inner joists are 2" x 6" spaced at 12" and hung with joist hangers.


Respectfully, don't like your design one bit. Right off, 2x6 floor joists are too small to span 10'.

If you are bound and determined to only use 4 posts, then at the very minimum I think you should use 2 support beams set back (cantilevered) from the rim joists. Cantilevering the 2 support beams would decrease the center span of the floor joists. Plus the beams would be under the floor joists providing maximum support for the floor joists.

The size of the 2 support beams and floor joists and overall design would need to be specified by an engineer or architect.

Maybe you could utilize your city's building permit department to help you design your shed. Design it and submit the plans to them for a building permit. They will tell you if your design does not pass and might even make suggestions on a design that will pass.

Regards,
HRG


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