Bit of decking advice. One for TMH perhaps ??

[Arfa Daily]

I'm intending building a deck in my back garden this summer. It's going to be the full length of the conservatory at just over 14m by about 2m wide for ten of that 14. The rest is narrower where it goes round the "D" bit of the conservatory. The garden slopes a bit, so at one end, the deck will be only just above ground level, but at the other end it will be 30 or 40 cms above ground. I'm intending having a level wallplate fixed to the brick conservatory wall, and the bearers coming off that at 400 mm centres. I am going to have a 'leg' at every second bearer along the front, and probably the same on the alternate bearers, half way across the width, so at around

1m out from the wall. Rather than sinking these legs into the ground and concreting them all, I was thinking of bedding a row of 40 cm slabs on gravel or whatever, right along the front edge to serve as a solid base for the legs to stand on, as well as giving an edge for the grass, and something to mow up to. I would do a similar arrangement for the middle legs, but just with a slab at each position where a leg would be. Does this sound ok so far ?

Now, my other query is with the material to use for the wall plate and bearers. The Wickes "How To" leaflet would suggest that if the deck is off the ground, then "treated stress graded joists" should be used. This seems a bit OTT to me. Treated I can live with, but joists seems a bit big and expensive to me. The 75 mm x 47 mm treated timber that they do is a reasonable price, and looks quite big enough to do the job, considering the amount of support I am intending giving it, and the fact that every deck board is double screwed at every bearer.

What's the general consensus on this from those of you who do this pro ? Is

75 x 47 going to be big enough to do the job, and is my plan to provide 'hard standing' for the legs, valid ?

TIA

Arfa

[MuddyMike]

Having just helped rip up some 3/4 year old decking at my sons house my advise is lay a patio, not decking.

Mike

[Arfa Daily]

And the point is, Mike ? If I wanted a patio, then that is what I would be laying. A properly built and maintained deck will last many more years than three or four and, having had patios, is IMHO much more decorative. Just as a matter of interest, what was the problem with your son's deck ?

Arfa

[The Medway Handyman]

Having built around 40 decks in the last 5 years I'd disagree :-)

[John Williamson]

I'll second that, but also for the reason that a lot of decks serve as shelter for pest colonies.

It's dry and relatively warm under there, as well as being hard for predators to reach and close to food supplies.

If you must, then build it high enough off the ground that the terrier can get at the rats.

[The Medway Handyman]

A deck more than 30cm above the ground needs planning permission. However most people ignore that and my local planning dept are unable to define 'ground'.

Space the wall plate 10mm away from the wall if its on or above the DPC. I use these

I am going to have a 'leg' at every second bearer along

That will be fine. I just bed the slabs down level on the earth, the load is spread over a very large area.

Treat the cut ends of the bearers with an end grain preservative & place a piece of DPC under them.

Are you intending to finish the front edge so you can't see under it?

How you going to attach the joists to the wall plate?

They also suggest 'slow grown' timber :-) The leaflet was written by a marketing guy, not a deck builder :-)

Treated you must have - no question. I won't use anything less than 100 x 47 - C16. I pay £1.62 a metre for that (delivered free) rather than Wickes £2 a metre for 75 x 47 ungraded.

Check out a few local builders merchants & timber yards. Also check out the price & availability of deck boards.

For a deck that size you are going to need 100m of joist, 200m of board (155mm) and about 1,000 screws :-) Let me know how close I am!

A 100 x 47 @ 400 centres will span 1.92m according to Table A of the building regs, so 2m for a deck would be fine & save a lot of work.

P.S. I'd quote you around £1500. Desmond & I could knock that out in 3 days :-)

Happy to help if you need any more info.

[The Medway Handyman]

None of the 40 or so I've built have. Neither have the hundreds of thousands of decks in the USA, Canada & Australia. Urban myth.

Its not. Deck boards have gaps mainly for expansion, but also for airflow & water drainage. Constant draft & dripping water, no food source. Much more likely to have rats under your garden shed.

[Skipweasel]

But then the cats shit under it and you can't get it to scrape it out.

[Arfa Daily]

That's interesting. What's the thinking behind that ? I'll probably be on the course immediately above the DPC membrane

Not sure. I was certainly going to have a 'skirt' along the front, but hadn't considered taking it all the way to the ground. Reasons you ask ?

What would you recommend ? I had considered both 'cutting them in' to each other and then skew screwing from either side, or joist hangers. Your thoughts or alternatives ?

C16 at that size is, I think, what Wickes recommend. £1.62 (+ VAT ?? I think the prices that Wickes quote include it) does seem like a good price, and I would be happy to use that if I could get it at that price. Is that from a 'national' or just some yard local to you ?

Thanks Dave. Much appreciated

Arfa

[jgharston]

Anybody who wants decking does.

JGH

[Ghostrecon]

I always use 100 x 47 for joists 'treated stress graded' in fact for a couple of 6' off the ground edges I used 150 x 47 iirc (helped suport uprights for rail)

[The Medway Handyman]

The space allows water to drain & air to circulate - keeps the wall dry.

Because then you cant see the bearers. I use the offcuts of deck board vertically.

Joist hangers

but screw them in with 2" screws.

Local, but the price isn't exceptionally good. Shouldn't be hard to find locally.

[Arfa Daily]

I must be thick this week, but I'm not making a lot of sense of what exactly (qty x sizes) they are saying is in the pack. Are any of them actually 10mm, or is it a question of just stacking them up to get combinations to 10mm, for this particular type of job where you want the same spacing all along, until they're all gone ? What spacing would you recommend screwing the wallplate at, and do you have any preference for the fixing type ?

Arfa

[The Medway Handyman]

Sorry, not the best link. You can buy 10mm ones

What spacing would you

I use the Multi Monti type

or

about 75cm apart - be easier to pull a sailor off your sister than move the wall plate.

[Arfa Daily]

> or

> Spaced about 75cm apart - be easier to pull a sailor off your sister than

Thanks Dave, all good advice and much appreciated. Just as a matter of interest, do you use a washer under the heads of those bolts to spread the force across the face of the wood ? And how many screws do you use per joist hanger ?

The project is now, I've today been informed by SWMBO, been relegated to number two in line. Following TTP quotes to build the counter for her new take away, it seems that the job is now going to fall to me ... d:-| }

Arfa

[The Medway Handyman]

>>>>> or

>>>>> Spaced about 75cm apart - be easier to pull a sailor off your sister

Never used a washer, as I said, easier to pull a sailor off your sister...

I use these to screw the joist hangers on

each side & 2 into the joist IYSWIM.

I use a bigger version M6 x 90 for joists.

[Arfa Daily]

I drew up the design today to do the workings out. Your first estimate on the timber is pretty damned good. I got to 103m ! There is a builders merchant just a couple of miles from me that looks like they will be able to do this timber at a good price, delivered, so I will give them a ring on Monday to get an exact figure.

Back on the joist hangers. Would you use them along the front edge as well, or would you screw directly through into the ends of the bearers ? If so, two screws per bearer fix ? 100mm length ? The same hex-headed ones that you pointed me at ?

Thanks

Arfa

[The Medway Handyman]

Directly into the ends, 6 x 90 turbogold coach screws.

Good excuse to buy an impact driver :-)