Deck on concrete slab only 4 inchs below damp proof course

Old 09-09-02, 04:50 AM
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Deck on concrete slab only 4 inchs below damp proof course

I am building a deck on a concrete path next to a house. Problem is that the damp proof course (DPC) of the house is only 4 inches above the concrete. This means the finished level of the deck will be just above or if I am lucky just below the DPC.

Good building practise say that the finished level of a deck must be at least one course of bricks below the DPC. I have pointed this out to the owner of the house saying he may get damp problems with rain bouncing off the deck onto the wall above the DPC. He is unconcerned about this so as the customer is always right how can I do this to minimise damp problems

Two sections of deck one 43 inches wide ,another 60 inches wide , each section about 10 foot long (this follows an L shape around the corner of the house). I intend to bolt the wall plate or ledger timber to the house wall.

I am thinking of using either 4x2 timbers on their side at 15inch centres or 2x2 at say 12 inch centres. If I use 2x2 then I plan to fix the timbers to the concrete every 18 inches or so with screws and wallplugs to stop the deck bouncing up and down.

Question is

1. Which size timbers should I use to make the frame with

2. To provide a gap between the frame and the concrete base normally I would use 2 inch paving slabs. Unfortunatly their just is not room. Can I used small bits of timber to raise the support beams off the concrete by say half an inch?

3 Is their any way to minimise rain spashing onto the wall I could fix a piece of decking vertically between the ledger timber and the wall leaving a gap of say one inch between it and the wall.

All in all this is a bit of a bodge and goes against doing a quality job but hey the customer is always right and I need the work!!
Old 09-09-02, 07:47 PM
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Deck on concrete slab only 4 inchs below damp proof course


It seems you have a dilema. Since I can't see this and it seems that you have experience at doing this, I recommend simply this, do what you think is best. Limit your liability in writing if the customer want's it a certain way or don't take the job.

Nothing worse than getting a bum rap for "what the customer wanted versus what is right!"

Your description is hard to follow but your reasoning seem valid. I would go with what you think should be done. No job is a bad thing, having a job go bad is even WORSE!

Good Luck!
Old 09-09-02, 09:22 PM
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Have you considered building a built in wall planter out of exotic hardwood or even PT with a decent stain? If you have 43 and 60 wide ..these sound more like walkways than decks. You could build out 7 inches to leave 36 on the 43 and similar on the 60. THat way you can have a nice low profile planter, decorative.. put inorganic mulch like stone down and seal the brick with poly behind it all with mastic or spray adhesive. No rain splash.. still a decent walkway size. I can see this turning into an asset rather than a liability. Play around with some ideas and see what you come up with. THe planter would only need be 12 or so inches high but maybe on the 60 inch you could do a tiered one 12, 18 .24 all 8 inches wide or so? Why not draw up some designs and present them to your client. Even graph paper sketches can be helpful. but its just an idea.

Hope this helps-Josh

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