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 tomorrow and I'm hoping for a quick answer so I can discuss with him.


enter image description here

In the picture 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.

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    I have too many concerns with this project to simply answer your question with a "yes". Drainage, structure, deck slope (which serves no purpose). I'd be looking for a second local opinion on all those things. – isherwood Oct 23 '17 at 15:36
  • @isherwood I understand that deck slope causes rainwater to run away from the house instead of towards it oand keeps it from sitting longer on the deck surface (mold, mildew, rot, ice, etc.). – Technophile Jun 28 '20 at 4:36

Yes make sure the earth grade around the entire house is sloped away from the house before and decking of structure is installed.


Your Deck Framing should slope away from the house, in our area it is typically 1/8 to 1/4 " per 3 feet so over a 12 foot run you would notice a drop of 1/2 to 1 " total thus washing water away from the house it should never drain towards. Also Make sure you properly flash behind any deck framing that is attached to the building framing and also flash above to drain water away from where deck framing meets house framing. also good to use metal spacers between house framing and deck framing which is very inexpensive cheap to use now versus later and keeps framing from rotting due to deck moisture.

  • You're suggesting that the deck itself should slope? What's the point of that? Decks are permeable. – isherwood Oct 23 '17 at 15:27
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    Yes most decks are permeable but water runs downhill and if your deck framing is level or piched in a manner that the deck is higher on outside edge tah it is where attached to the house than that means that any moisture whatsoever will travel from the floor rafters towards your house, thus creating an area at the house that will be subject to constant moisture and eventual rot, just google decks rotting where attached at house and see the damage moisture can cause. A 1/8 to 1/4 inch slope over such a long length is not even noticeable when walking on it but definitely noticeable to water – Timberframer Oct 23 '17 at 16:06
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    furthermore if using wood framing structure it also helps to put a strip of 4 or 6 inch butyl rubber sealant tape along the top edge of the floor rafters before the decking is installed as this helps to prevent the rafters from rotting out where the decking is against it as a result of the moisture trapped between the rafters and the decking. – Timberframer Oct 23 '17 at 16:08
  • That much slope won't prevent the conditions and damage you describe anyway. Proper flashing will, of course. – isherwood Oct 23 '17 at 18:08
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    "Floor rafters"? Do you mean joists? – isherwood Oct 23 '17 at 18:08

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