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waterboy
Junior Member
Joined: 18 Feb 2006
Posts: 13
Location: Norfolk
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 Posted: Thu Mar 29, 2007 11:23 pm Post subject: Decking |
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Hi Everyone 
I am thinking of doing some decking for a friend, I know that for a raised deck you have to sink supports into the ground and concrete etc.
But the friends house has patio doors at the back and there is only about a 4 inch step down onto the garden  does this mean that I will have to dig the garden out?
Is it a good idea to use joist hangers on the wall of the house and work outwards from them?
Thanks for any replies |
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skiking
Senior Member
Joined: 13 Sep 2006
Posts: 3086
Location: Cheshire
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| Posted: Fri Mar 30, 2007 7:50 am Post subject: |
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| Take a look at this |
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Fri Mar 30, 2007 6:28 pm Post subject: |
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it sounds like you need to remove some of the patio and you need it to be at least 50mm below the bottom of the subframe
personally id fix a wall plate, spaced off the wall (so you dont hold damp against the wall) and fix the joist hangers to the wall plate.
some people call the wall plate a ledger
second fix the plate at a level such that the finished surface of the deck is 150mm below the damp proof course.
150mm is a building regs requirement to prevent water getting above the damp proof course
if you do this you wont get a future claim for CAUSING damp in their house
you do not want a claim from the householder when |
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waterboy
Junior Member
Joined: 18 Feb 2006
Posts: 13
Location: Norfolk
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| Posted: Fri Mar 30, 2007 6:40 pm Post subject: |
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Thanks for the replies
Dirtydeeds- that is exactly what I wanted to know, thanks very much |
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Fri Mar 30, 2007 7:07 pm Post subject: |
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waterboy
if you are in a part of norfolk where the subsoil is pure sand you JUST MIGHT be able to get away with digging only 1 inch below the bottom of the subframe but i wouldnt recommend it
if you are in the fens with peat as a subsoil, 50mm might be cutting it fine due to ground heave
whatever you do, i suggest you use treated joists for two reasons
there is little air flow below a deck. reason no/low air flow = damp = possible rot
treated joists tend to be regualrised so the work is easier |
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Marc
Member
Joined: 29 Jan 2007
Posts: 67
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| Posted: Sat Mar 31, 2007 11:40 am Post subject: |
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| 6" below the dpc is difficult on many houses and if the dpc on this property runs directly under the doors he is going to need a lot of digging out. |
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ultimatehandyman
Site Admin
Joined: 16 Jul 2005
Posts: 9740
Location: Darwen, Lancashire
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| Posted: Sat Mar 31, 2007 12:27 pm Post subject: |
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| Marc wrote: |
| 6" below the dpc is difficult on many houses and if the dpc on this property runs directly under the doors he is going to need a lot of digging out. |
I was thinking that!
If the floorl level is level with the floor in the house you may have to dig down 12-14 inches to accommodate the joists and the 6 inches below the dpc 
Most of the decking that I have seen is level with the floor of the house, as long as the decking does not touch the house and the wall plate is spaced from the wall using plywood would it not be ok?
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Sat Mar 31, 2007 3:01 pm Post subject: |
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dont space using plywood it can rot and it also holds water
think about stainless steel washers, plastic anything that wont absorb water, the gap needs to be as open as possible i would suggest 10mm, much less and it will trap debris and this will bridge the gap and let damp against the house
as to questioning if decking can be at the same level as the dpc
decking CAN be set at the same level as the dpc, however building regs are in place for good reason. you CAN choose to ignore them if you so desire, its just not a good idea |
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Marc
Member
Joined: 29 Jan 2007
Posts: 67
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| Posted: Sat Mar 31, 2007 3:11 pm Post subject: |
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You are right DD but you would be turning down quite a few job sticking to that rule. I've explained a few times to customers that the deck is close to the dpc and they don't care. Its a case of "if you won't do it somebody else will".  |
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Sat Mar 31, 2007 5:14 pm Post subject: |
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i have no problem with working to the customers requirements. written quotes are a good way of recording customer requirements that are not in accordance with regulations
there is one customer requirement i ALWAYS refuse
the one where they ask you to work off a ladder to save them the cost of a scaffold or tower |
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ultimatehandyman
Site Admin
Joined: 16 Jul 2005
Posts: 9740
Location: Darwen, Lancashire
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| Posted: Sat Mar 31, 2007 6:35 pm Post subject: |
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| dirtydeeds wrote: |
dont space using plywood it can rot and it also holds water
think about stainless steel washers, plastic anything that wont absorb water, the gap needs to be as open as possible i would suggest 10mm, much less and it will trap debris and this will bridge the gap and let damp against the house
as to questioning if decking can be at the same level as the dpc
decking CAN be set at the same level as the dpc, however building regs are in place for good reason. you CAN choose to ignore them if you so desire, its just not a good idea |
I'm doing some decking soon at a friends house, I have not seen it yet and so I don't know what to expect! I'll make sure I use some 10mm pieces of perspex to keep the wall plate from the house 
Hopefully I can get an half decent "how to deck" section on the site then
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Sat Mar 31, 2007 8:00 pm Post subject: |
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other tips, mainly to do with butted joints on deck boards
dont but joint over a single joist as you would with floor boards, it is a water trap so you can get rot very quickly.
also screws this close to the ends of boards (they will be only 8mm from the end if fixed over a 38mm joist) WILL split them.
split board ends looks unsightly, looks unprofessional and helps rot
overcome this problem by putting in a double joist at the butt joints, again a minimum gap of 10mm is usefull, this way you get no water trap
to find the position of the double joist you need to plan the final layout of the decking in a regular pattern, sort of like house bricks
regular joint layout looks planned and professional
final bit on screwing near the ends of boards. predrill the boards in this position to further reduce the chance of splitting the board
external board ends
let the ends of the boards run over the end joists and cut them all in one go, its quicker
finaly take a router and roundover or chamfer the cut ends, it is attention to the details that gives a professional look to a job, to prevent splitout the router has to be used right to left (the wrong way round) sometimes called a climbing cut. |
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ultimatehandyman
Site Admin
Joined: 16 Jul 2005
Posts: 9740
Location: Darwen, Lancashire
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| Posted: Sat Mar 31, 2007 8:03 pm Post subject: |
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Thanks DD, some great tips there
Is it not difficult cutting the decking where it is close to the house wall?
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Sat Mar 31, 2007 8:24 pm Post subject: |
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if you are laying the boards paralel to the wall, scribe the first board to the wall, but remember to fix it 10mm from the wall, nothing looks so bad and unprofessional as an irregular gap
what you are looking for is an equal gap the whole length of the wall
another thing, pick out the straightest boards for this job
if the boards run perpendicular from the wall of the house use a spacer, 10mm is good
if the boards run perpendicularly from the house put a small fall on the subframe so the water tends to run away fron the house, but not so much fall that you will notice it when walking on the deck |
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dirtydeeds
Craftsman Carpenter
Joined: 30 Sep 2006
Posts: 256
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| Posted: Sat Mar 31, 2007 8:54 pm Post subject: |
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without being too obvious, the 10mm gap between the hosue and the edge of the first decking board is the ONLY place on a deck where the gap between boards is 10mm
unless you are fearless in the face of a lady who has just broken her stilletto heal  |
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