Building a deck

[No skills]

You will need to pitch the length of the deck boards (left to right or right to left if the boards are parallel) assuming I'm reading your description correctly. That would mean the wall plate/ledger will need to be pitched.

You seem to be overthinking the job Your basically building a suspended timber floor that will have a slight pitch to encourage water to run off, handrail/stairs etc are not majorly affected.

 

[rafezetter]

Something I thought I'd mention that's repeated several times on US program called "disaster decks" is not to bolt the wall plate directly to the wall if it's timber - use offcuts as spacer blocks to allow ther air to get between wallplate and wall otherwise it'll remain wet for days after it rains and obviously speed up the degradation time.

The other method this program mentions is to put flashing over the wallplate, but that's usually done if there is some form of cladding on the wall, I guess you MIGHT be able to get away with using a DPC layer and wrapping the wallplate, but the block spacers method is much simpler.

Don't skimp on the wall fixings either - I'm, not sure what the recommended spacing is, but I wouldn't just rely on vertical supports and a few fixings.

 

[KevB]

Cheers for that No skills and rafezetter. Haha and yes No skills i'm really bad for over thinking things :lol:

Ok so ive done a plan of the framework, support posts and rail posts. Can you guys tell me if this looks ok? The deck is 4.5m x 3.5m.

The squares with x in them are the support posts and the shaded squares are the rail posts. The framework is all 6x2 and the joists centred at 450mm. The first row of support posts are centred at 637mm from the ledger board. There's also a gate to the left hand side with an opening centred at 825mm.

Do any of the support or rail posts look too far apart? I do have cost in mind but I also don't want a bouncy deck or wobbly railings.

 

[No skills]

Looks pretty fair I think.
2 points I think, the handrail post spacing MIGHT need to come down a little - or maybe not... bit of a suck it and see job really, kinda depends how solidly you can get the posts fixed to the joists and how sturdy it all gets when the rails and spindles get fixed between them.
I would make up a test section once you've got the framework done and have a bit of a push and pull on the posts and rails and see what you think.
The other thing is how good and straight are the timbers your going to use for the 3500 runs? If you can get 10 or so really good ones then no problem, if some are not that good then you'll end up with puddles forming on the decking where the dips are. My own deck has one spot that does this and it bugs the **** out of me
It might not be an issue for you, if it is and the timbers aren't great then divide the 3500 into 2 with a pair of joists going left to right in the middle - that then gives you 1750 lengths (to cut out of 3.6 or 4.2m lengths) which are easier to fiddle with (to pack up or to plane bits off etc) and get straight.
Not sure if that reads right but there you go

Hth

 

[No skills]

Oh and don't forget to noggin it to death, it really helps with strength (spreading load by making the joists work together) - if you can cut the noggins in nice and tight it will also go towards keeping the joists straight as they dry out.

 

[KevB]

Hi there No skills.

Thanks a lot for the advice, really appreciate it.

Yeah I agree about the railings spacing. I originally drew it out with an extra post down the left hand side and another along the front. Giving me 4 down each side and 5 along the front. After looking on youtube, the railing posts all seem to be around 1-1.2m apart, rather than 1.5m plus. For the sake of an extra £15, i'll probs add the two extra posts in to be on the safe side.

The timber will be from a place called Quay Timber in Newcastle. It is advertised as Sawn Timber Treated Regularlised C16 FSC. Do you usually get straight lengths if it's C16 graded? I'll be ordering the timber online so I wont get to see them first.

If the timber isn't great, then like you say, I could make the frame in two sections.

A few other questions..

How high do the handrails need to be above the deck?

Do the post holes have to be 700mm deep for this size decking? If so, will one bag of postcrete be enough for each hole?

 

[KevB]

Ah, I've just learned that 'regularised' means the timber is of consistent dimensions, so hopefully all of the lengths will be straight and bow free.

Was going to go for 47x150x3600mm at £9.47 a length, which looks like the cheapest around.

 

[Paul200]

Hi Kev

My handrail posts are 4x4 and about 1.2m spacing. They go down through the deck into 'sockets' built into the base frame (basically a square of framing timbers). They are held in place with chunky coach screws. Nothing worse than a wobbly handrail!

Paul

 

[KevB]

Hi Paul

Thanks for the reply mate. Can you remember what size coach screws you used an how many in each post?

Toolstation sell them up to M10X150 (exterior), though at £19.33 for 10, I find them quite expensive. They also sell exterior coach bolts, nut and washers M10X160 at £12.95 for 10 or up to 220mm in length.

That sounds exactly the same as I had in mind for my rail posts. Set them flush with the bottom of the frame and then box them in, to minimize movement.

Do you have a double handrail at the top?

Also, when adding the noggins, could I use 4x2? I have around 5 long lengths of this in my shed and if it could save on costs, it would be nice to use it.

 

[Paul200]

If I remember I think I used M10x120. Two through a main structural timber and then one more at a right angle to those. Most big sheds are expensive for fixings. I used to sell them for about half that price! Try to find a small independent business (but I know they're few and far between these days). You could use threaded bar with a nut and washer at each end - much cheaper.

Not sure what you mean by a double handrail?

Yes, use the 4x2 for noggins by all means. They're not majorly structural - they just tighten everything up.

Cheers, Paul

 

[KevB]

Hi again Paul.

It did cross my mind to use threaded bar and Toolstation seem to have a good price on it.

M10X1M lengths - £2.05,
Nylon Lock Nut M10X50 pack - £2.06
Heavy Washer M10X100 pack - £2.48

Is 'zinc plated' ok to use on decking? I ask because there seems to be a big price difference between 'zinc plated' and 'exterior (Outdoor green, corrosion resistant)'?

I watched a video whereas they used a handrail on top of a handrail, I think it was to hide the screws going down through the spindles. I'm trying to think of the best way to build and attach the railings without any or minimal screws showing

 

[Paul200]

Ideally you would use stainless steel outdoors but I used zinc plate - you can't see it under the deck - it will rust and eventually rot but I won't be around to see it :roll:

Not sure about the green phosphate coating but I googled it quickly last night and it seems to do a good job at resisting rust. Your call really - it takes a long time for a steel bolt to rust through (unless you live on the coast of course!).

My handrails are screwed from underneath on the skew through the side of the spindle, but all my timber is rough sawn and the heads of the screws disappear among the 'whiskers' :wink: I used rough sawn timber because it's more in keeping with the rough old area - very agricultural, rustic and wild :lol: Nice clean lines just don't look right here - and it makes my job a whole lot easier!

If you're using planed timber you could use the same method to fix the handrail but lift a sliver of wood with a chisel first, drill the hole under it, pop your screw in and glue the flap of timber back down over it - if that makes sense? Saw it on a Youtube vid once but damned if I can find it again - not even sure what search words to use :? You just need to make sure you don't remove the flap - just lift it - like a trapdoor, still attached at one end, that way it blends back nicely. A lot easier than plugging a slanting hole!

I also fixed the ends of the handrails to the uprights with stretcher plates - again, rough and ready, but it works!

Cheers mate, Paul

 

[Paul200]

(unless you live on the coast of course!) - just realised where you live!! Scratch that then - you should probably be using stainless mate!

 

[KevB]

Cheers for that Paul.

Stainless steel and even the green phosphate is probably going to be above my budget I reckon. I may take a risk with the zinc plated fixings. I do live in Whitburn, though it isn't right on the coast, maybe inland by half a mile or so, if that's going to make any difference to the lifespan of the zinc lol. I guess i'll have to see how much my budget will stretch as I'm going to need quite a few fixings to put everything together.

Good idea about the flaps aswell, I'll have a look into it and see whether it's within my capabilities or not

My brother works with a cnc machine and i'm going to ask him if he can make me all of the various brackets and plates I will need. Joist hangers, handrail brackets etc. If I'm lucky i'll have a choice between galv, aluminium and stainless steel.

On another note. I'm still waiting on the council replying to me questions regarding planning permission. Apparantly they are short of staff and they have nobody available yet. It's only been around 5 weeks! Cant wait to get started