How do I repair an outside timber dunny as a tiny shed?

[JammCassie]

Hi everyone, I have a dilapidated timber dunny that was rotten at the base. It is in the backyard of a heritage listed regional schoolhouse and it was once the boys toilet. The supporting timbers went directly into the ground and given it is about 100 years old, they finally gave way. 

The plan is to repair the shed, replace the corrugated iron at the back with matching timber weatherboards, replace the leaking corrugated iron roof, put on a new (old) door and put it in the corner of the old tennis court to house bats, balls and outdoor games.

But my first question is - what do I need to do to anchor it to the ground and what would be the best base for the shed. What do I need to do to prepare the ground; should I use a timber framed support or a small concrete slab and how do I go about repairing the bottom timbers and affixing it to the floor (whatever it should be)?

Side viewBack viewRotten timber bottomInside the shedInside the shedFront view

[EricL]

Hello @JammCassie, 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your tin shed conversion.

I suggest using 90 x 45mm Outdoor Framing H3 Treated Pine - 2.4m to rebuild the bottom plate of the stud wall. If the bottom of the timber pieces have rotted away, I suggest cutting the rotted portions off and attaching new pieces to maintain the height of the shed. I recommend pouring a slab for long term stability and to prevent the base from rotting again. Once the shed frame has been repaired you can anchor it to the concrete base using Dynabolts or AnkaScrews. Please don't forget to use CAgroup 110mm x 30m x 500um Plascourse to protect the bottom plate.

Here is a handy step-by-step guide:  How to pour a concrete slab by @tom_builds 

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you need further assistance, please let us know.

Eric

[JammCassie]

Thanks so much Eric, that a great place to start. I have a very basic question on the concrete slab - previously I had a house with a steel shed in the back on a concrete slab which was a little bit bigger than the shed. When it rained, water would come in under the shed walls and pool inside. So what size concrete slab should I be pouring versus the current toilet/shed base, and how do I stop water coming in under the walls.

Also I've never used Plascourse before. How do I use it, and is there a tutorial for it?

Thanks again, I really want to try and do this one myself.

[Dave-1]

Good Morning @JammCassie 

Now thats a project and a half  @EricL 's suggestions are bang on the way I would be stepping through the redo.

With the slab, Maybe make it an inch smaller then the outside of width of the walls, thatw ay when water hits it, the water will drian to the ground.

I like stirrup supports for longativity, but trying to stay as close to teh original of the outhouse I would go with the bottom plate that @EricL has suggested.

If you wanted to step off the concrete then you could use stirrups as standoffs Pryda 65x90mm M10 Full Stirrup Post Anchor 

Dave

[EricL]

Hello @JammCassie 

One option to prevent water from flowing into the tin shed is to raise the interior part of the slab. You'll need to measure the interior floor space of the shed and build a secondary formwork for the higher section of the slab. The plascourse basically goes under the bottom plate to serve as a barrier between the slab and timber frame.

If you need further assistance, please let us know.

Eric