Raised decking

[vinylspin]

Hi all,

Since I was unable to source matching paving slabs to finish a small area (left on the pic) due to some reworks and my missus prefer decking here I am for some advice.

I am planning to build decking to the same level as the kitchen/dining floor. The decking area will be slightly bigger than the existing patio 5.6m x 3.3~3.5m (5.6 x 2.8m).
Considering the slabs are solid with no movement I am thinking of living them intact, fix bolt down mounts with 4x4 posts, then bolt 6x2's onto them to build the frame with 400mm noggins.

My concern is about the DPC and air bricks as the decking will be over them. I plan to leave 10mm gap between the back board and the wall to allow for air circulation. I guess anchor masonry bolts are ok to fix the back board, but what size board and bolts should I use, are there any standards for this?

My other dilemma is which way to fix the decking boards, parallel to the house would be less slippery, 90 degrees to the house would look better and would allow better running off of the water, what are your thoughts?

Thanks in advance

 

[ABCwarrior]

DPC's are usually 150mm above ground level, so if you install decking which is above this then any splashed rainfall will affect the walls above this. How serious this is is maybe a matter for you to decide- ie do you live in an area where it rains a lot, is the wall exposed to prevailing wind/rain or sheltered?

As for the direction of decking- I'm doing mine at the mo and we've gone for perpendicular/90 degrees to the house. Everyone says I'll slip on my arse when it's wet/frosty....but then walking along the other way it'll be fine. Decking is 2 dimensional- it'll only be marginally less slip proof in one direction!!! As you mention it's easier to get a water run off going away from the house and in Feng Shui terms looks a lot better, drawing your eyes to the drystone wall I've built in the garden...

 

[freddiemercurystwin]

Decking should always be parallel to the house. Any other way is just daft. Google some images of decks if you like and see.

Fit it level with your threshold and keep a 10mm gap between the first deck and the wall, the frame under can be a little further from the wall. Don't fix anything to the wall there is no need. There is also absolutely no need to bolt your frame down onto the slabs. The whole lot will just sit there under its own weight.

 

[vinylspin]

ABCwarrior and freddymercurystwin, thanks for your prompt replies.

We are based in NW London and the wall is facing SE.

I am still in two minds re direction of the boards, perpendicular/90 degrees to the house would be simpler to install and one of the main reasons for this method is also the length of the boards as standard is 3.6 or 4.8m so I could avoid cutting if I use 3.6m.

Surely bolting down would allow me to fix 6x2's to the posts hence raising the frame which would be better for wood longevity and it would also be more economical, otherwise I would have to build double frame to achieve wanted level?

 

[freddiemercurystwin]

Your frame will be rigid whether its bolted down or not. Or you've not made a very good frame. Unless you raise your timber off the surface of the slabs you will get timber decay whther you use posts of joists first. Only way to avoid that is to avoid the contact between the slabs and the timbe ie use 'decking supports'; Google 'em.

The weight of the deck even when bone dry in the summer months it will still weigh a ton and you won't get any bounce etc.

Decks are built this way on flat roofs all the time.

 

[vinylspin]

I was thinking doing something similar to this (support wise)
//www.diynot.com/forums/viewtopic.php?p=1663764#1663764

 

[freddiemercurystwin]

And there's nothing at all wrong with doing that either. The point I am making is that bolting each post down to the slabs is a waste of time, money and energy. Furthermore should you or the next owner ever wish to return to paving the deck can simply be scrapped leaving the patio intact without random holes all over the place.

 

[vinylspin]

Freddy, thanks again. I never thought about that, although we are unlikely to re-use the slabs your point is very valid.
I think I will go with that and set a few posts in the ground near the end of the slabs as the new deck will be longer for approx 2ft.

Do you have any tips on how to construct the frame since I need to achieve approx 13" height before the boards are laid down?

Sorry for so many questions, but I have seen all sorts of deck support frames by searching on google.

In addition I am toying with idea of building also a seating area in L shape to maximize the space.

 

[freddiemercurystwin]

If it were me I'd be doing something like a subframe of 6x2's at say 1800 centres then a further frame on top of that at say 500 centres and sit your decking on those.

Depending on the direction you end up doing your decking will determine the direction of your subframe. You could use a couple of deck supports under the first subframe to raise them off the patio which would keep them out of sitting water and would enable any rain to drain away too.

 

[maltaron]

It will be very nitpicking if anyone shops you but you state 13" before boards. That is higher than 300mm and technically needs planning permission.

 

[vinylspin]

Thanks for your input, but I re-measured it and I will be building the deck within 30cm