Advice needed about laying decking

[djmagnifique]

i'm going to be building a small area of decking in the garden (3.3m x 1.5m approx) and need some advice.

1. how deep into the ground do I need to set the posts? I've had a look around on the internet and have found info saying anything from 0.3m to 1.2m below ground level.

2. About a quarter of the way along the short edge is an inspection chamber, should I make a removable section to allow access or should I just cut the deck boards into shorter sections and double the thickness of the joists in this area so its less work removing them if access is required?

3. Most of the decking is going to be away from the brickwork of the house however there is a small section that will be in contact with the brickwork (about 0.5m) and I was just going to fix a support beam to the wall to fix the boards to. How do I tell if this will be below the damp course? (the height it will be at is below the level of the floors inside the house)

4. I can get some posts (100mm x 100mm) and wood for joists (100mm x 50mm) for free (they have been treated for outdoor use), will this be suitable to use for the framework and if so what length screws should I use?

5. The deck boards i'm going to be using are 25mm thick, should I use 50mm or 75mm deck screws?

Cheers.

If I can get my camera working i'll get some pics of the garden as it is now so you can have a better idea of what i'm planning on doing.

 

[Pinnacle]

1. Depending on how high you are rasing the deck will depend on how big the posts need to be. Either way the easiest way to work it would be 1/2 underground set in concrete and 1/2 above the ground. (This doesn't apply to posts that will be supporting hand rails etc). It's a good rule of thumb to place the posts on top of a couple of engineering bricks at the base of the hole beforeyou fill it with concrete. Another tip with the posts if you have enough, set them first then cut them down to size nce the are set. This will way you can cut one, make sure it's flat and level and use a laser spirit level to mark the cut on the others. This is the easiest way to get level decking. But remember you need to flow any drainage away from the house, so you will need a slight angle for drainage.

2. I would say a removeable section is your best bet. It's not going to be used a great deal so you could even scren this down in place and then just unscrew when required.

3. There shouldbe a change in colour of the external bricks in the house wall. This usually indicates the damp proof layer. You have to remember though to comply with Building regs (which also effect decking), no part of your decking can be physically within 10mm from your house. Therefore any wall plates you wish to attach to the house need to be seperated by 10mm spacers (a bunch of washers making up 10mm). Same applys to the deck boards, you need a 10mm gap between them and the house wall.

4. The 100x100 posts and 100x50 are fine for decking frames. Usuallly you would want to use 150 x 50 for the frame work but you can still use 100 x 50, you will just need to add additional noggins or put them closer together. As for screws again, same as posts half and half is your rule of thumb. so 100mm screws would see your frame work secure. However it's reccommended to bolt the frame either sideof the posts i.e. frame | post | frame and a coach both that goes through all three. This is especially the case if it is only supported by the posts and not the existing floor surface itself.

5. 50mm deck scres are fine. Again half or more in theanchoring side and you are fine. No point in going for 75mm as although these are fine to use it's a littl emore over kill and on a big decking ears will work out much more expensive (especially at £14 a box of 100).

Hope this helps.

 

[Pinnacle]

Forgot to add.

When you concrete your posts in , dome the top of the concrete slightly to allow better water drainage from around the posts.

 

[djmagnifique]

Thanks for the advice.

Here are some pics of my garden as it is now.

1. The decking will come just past the 2nd step from the top of the picture and will be at a level height with the top step. the height of each step is 150mm.

2. The location of the inspection chamber. I will need to put a post just in front of the chamber. The fence was put up before I moved into the house.

3. The small area where I would be attaching to the wall. There is no change in the brick colour (the house was built in the 70's I think and is an ex council house), however the floors downstairs are solid.

Also are the bricks I have here any good for putting in the bottom of the post holes?

Any other advice is greatly appreciated.