One for the builders (Re Decks)

[Sir Stinkalot]

With the Stink having a few more weeks off before returning to work the Stinkette has commissioned him to replace the steps that he removed about two years ago, affectively rendering the side and rear doors of the house useless.

Now as I normally design, not build, I have come humbly to ask the advice of the builders on this forum.

Attached is a JPEG of what I am looking at doing. The deck and stairs are, 500mm above ground level, the landing is to be 3000x900 with steps at the end. I want to use decking timber for the stair tread so the main deck direction needs to be perpendicular to the house.

Here are the plans.

Attach 290x45 TP ledger to the house.

Put in the three posts along the long edge and one in the middle. The additional post along the long edge is to attach decorative decking boards vertically along this face.

Put the two bearers (290x45) in running perpendicular to the house, and a joist (290x45) running parallel.

The joist will be supported in the middle to prevent any deck bounce.

Attach the middle joist 290x45 TP to the bearers with joist hangers

Add on the decking and the stairs and we should be done.

I was thinking of using post stirrups set into the concrete but the last time that I tried this the concrete shrunk when drying and the stirrups wobbled ….. what did I do wrong?

Now if there are any problems with the above please state your case now …..

Ok one final question ….. I have sized up the joists and bearers (290 x 45) with the assistance of Allan Staines “Decks and Pergolas” …… timber this size will cost me $14.50 plm for treated pine. Please tell me the reason why I can’t use 200 x 50 TP Sleepers at $15.00 for a 3m length. I know that the book says 290 x 45 but I can’t see much difference with the 200 x 50 as I am only spanning 1500mm at most. As the deck is only 500mm from the ground it isn’t going to kill if it fails but I have a fear that the sleepers will warp all over the place. I am just interested in hearing opinions before purchasing the timber.

Thanks

Sir Stinkalot

[journeyman Mick]

Stinky
welcome back, long time no poll! Being an architect and all you would know that a picture speaks 1K words. I started reading your description of your plan and just dazed out (still in holiday mode myself). How about a drawing of what you want to do? It doesn't sound right to me, but, like I said I just started dazing out reading it.

Mick :confused:

[Sir Stinkalot]

Hi Mick ..... I was hoping that you would be out there. I have attached a JPEG with my good self standing at the door .....

[Sir Stinkalot]

A plan view

[journeyman Mick]

Stinky,
according to my tables an 1800 span joist only needs to be 120 x 35 in F4, so a 200 x 50 sleeper should be just fine. The same tables show a bearer 1200 span @ 3600 crs to be 140 x 70 in F4. I avoid stirrups as they do tend to flex if the post is not braced in two planes. I prefer paired fish plates as they give a much stiffer post which requires less temporary bracing during construction. Less bracing = less timber, pegs & time. I usually screw or tape them to a scrap packer to get them the right distance apart and push them into the concrete once it's been placed.
One problem I can see though is your stringers. You'll need to have a centre stringer in order to support your decking at 450 crs. Even with that support it may still flex too much as you tend to apply more load when walking up and down stairs. I would sugggest that you spend the money saved on your subfloor (and by deleting a 3rd stringer) on more substantial treads.

Mick

[Sir Stinkalot]

Thanks Mick ..... I knew that you would come up with the goods.

I think that my timber sizes must have blown out a little when I was drawing it up and threw in a few more posts.

I wanted to use the decking timber for the stair treads as I prefer the continuous look of having the decking and treads out of the same material. I had always planned a third and possibly fourth stringer to prevent the step bounce.

So in your opinion do you think that the 200 x 50 TP sleepers will be adequate to build the sub structure out of? I am concerned over any warpage or splitting. I know that the size will prevent any bounce but I am concerned that the sleepers should be left in the garden and not the deck.

[DaveInOz]

Um ..... whats a fish plate?

[silentC]

So in your opinion do you think that the 200 x 50 TP sleepers will be adequate to build the sub structure out of? I am concerned over any warpage or splitting. I know that the size will prevent any bounce but I am concerned that the sleepers should be left in the garden and not the deck.

I reckon that there's every chance they'll warp or twist. Sleepers are nearly always delivered green and sopping wet. I've got some in the ground that have held their shape fairly well but I don't think I'd like to build anything on them and expect them not to move. You're better off getting kiln dried T/P. You'll also find it easier to work with.

[silentC]

Um ..... whats a fish plate?

Poisson du jour.

Two steel plates with holes drilled, one either side of the post with the ends embedded in concrete and bolts through the post. Same thing they use to join railway tracks, which is where the name came from, although I'm not sure why "fish plate".

[DaveInOz]

Poisson du jour.

Mate, sounds like a red herring!

Ta

[silentC]

A fish plate is a metal or wooden plate that is bolted to the sides at the ends of two rails or beams, to join them. A fish plate does not have anything in common with the aquatic fish. The fish in this term is derived from the French word ‘fiche’, meaning a peg. ‘Fiche’, in turn, is derived from the old French word ‘fichier’, which means to fasten. Thus a fish plate means a plate that fastens.

Doncha love the web?

[Fat Pat]

Now you are just CARPing on!

[journeyman Mick]

All the fish plates I've ever seen have a split up the middle of one end with the two pieces curved, one up, one down. I'd always thought they were called fish plates because of this "tail".

Mick

[silentC]

Wouldn't be at all surprised if that was true...

[journeyman Mick]

Stinky,
I've never used anything other than hardwood for subfloors. I don't think I'd feel comfortable nailing a deck into treated pine joists. Pine just doesn't hold onto nails that well resulting in popped or squeaking boards. I guess I would consider pine joists if I was using Dektights. These are a small metal bracket that nails to the side of the joist. It has two spikes that sit on top of the joist and the edge of the decking is spiked onto it. This way the nails are in shear rather than being pulled straight out.

Mick