Slope of decking and foundation

[sid999]

I'm having decking installed and the boards currently slope towards the house. The underneath of the decking is soil and there is no gutter alongside the house to funnel the water to the drain.

Is something I should bring up with the builder? It is early stages of the build. Only the supporting frame and 4 boards have been placed.

Apologies if this has been asked before, but the builder is due back later today, maybe tomorrow, and I'm hoping for a quick answer so I can discuss with him.

[Decking Area #1](https://i.imgur.com/SlT7N0l.jpg)

In the picture linked above you can see:

(A) Is resting on top of the paving stones and it appears that this is causing the slope towards the house. See D.
(B) If A was to drop to be flush with B, then the decking area would be level and the slope towards the house would be gone.
(C) This post, as with the other post, are not in concrete. They are about 2-3 inches into soil and are held again A with a single nail.
(D) This shows the direction of the slope towards the house.

You will also notice that the whole area rests on soil.

 

[r896neo]

This looks like a bit of a horror show. Although its hard to know what the standard is if its not finished they may still adjust and fix certain bits. Some people will build the frame as shown and then puts the concreted posts in after as it makes it easier to get them in convenient positions etc. If he is carrying on boarding then that suggests he is done with the frame and that would be concerning.

Some fundamentals,

Joists must be supported by something, If you were laying over an old patio or paved area then you can simply pack the joists off the firm surface with offcuts of slabs for instance. If however the area underneath is earth then you would normally concrete in posts every 1.5m and secure the joists to these. You can also use a small pad of concrete underneath a breeze block or similar but posts are easier and much more common way to do it.

Decking must have a fall/ slope. It need only be very slight but it needs to be there to shed water. something like 1:80 is enough. Falling towards the building is foolish.

Joists should be clear of the ground whether that is mud or an old patio, they need to be at least a couple of inches clear for water and air to pass around them.

The area under a deck needs to either be free draining earth or sculpted to make the water fall to a certain area where it is collected into a soakaway or into drains.

The vertical post i assume is for a handrail and fixing only to the frame is common although a full height concreted in post is far far superior.

 

[sid999]

Thanks @r896neo for your reply.

He showed up this morning and I mentioned about water being directed towards the house. He is now going to dig a small trench alongside the house and put bricks/stones (forget the exact words) in there is help guide the water towards the drain at the opposite end. He also forgot put place weed membrane (after I had mentioned it to him), so now it will be nailed to the top of the frame and the boards placed on top.

It's a bit difficult to question his methods without fully understanding the best practices/standards when it comes to installing decking.

Not too sure how to approach this.

 

[Keithmac]

Maybe building it yourself may give better results!.

Surely weed membrane should be on the soil?.

I would want the water running way from the house unless there's a very good reason otherwise.

We have a "French drain" at the back but the patio is also sloped away from the house.

 

[sid999]

Well from what I can tell he hasn't put a trench alongside the house. He has moved the boards so they are not in contact with the house. He has filled the gaps with gravel/stones, so the water will drain off and under the decking. Hopefully that will be sufficient and not cause any issues in the future.

 

[r896neo]

Contractors who come up with the easiest half assed solution to problems should be regarded with caution. Even more so if its a response to you bringing up issues!!

The solutions he has offered are the easiest option for him but a bad result for you in the longer term.

There shouldnt be a french drain next to the wall, he has purely offered that because you brought up the problem. Its a bodge to cover up his poor planning of the layout.

I would also imagine the decking may be level with your dpc which would mean any kind of trough here will cause damp problems in the house.

Post some pictures of the level at the house. I would recommend ceasing work until your are happy with the plan.

Putting a membrane on top of the joists is again an the absolute easiest option for him but terrible for you as it will just help hold moisture and dirt and grime between the boards leading to premature rotting. It is acceptible to staple a membrane to the bottom of the frame rather than lay it on the ground but it is no good laying it on top to gather up dirt as i mentioned.

 

[sid999]

I will post some pics soon.

Most of the decking is done. He has assured me it is fine, he has done this before and it's a viable approach. It's hard to argue against this without any evidence/knowledge to the contrary. Tempt to get a second opinion on whether any potential issues could arise.

Just hope he is telling the truth and I'm worrying about nothing.