4 Apr 2006
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United Kingdom
Hi all,

I am going to lay decking in my mothers garden next week. I have researched thoroughly and am well prepared and financed to do a 100% by the book top quality materials job that involves removing a patio digging out large area, digging 24 x 2' post holes (concreted posts)building frame as per best spec i could find (the one that uses most wood and sundries) and a composite decking board guaranteed for 25 years.

Having read a few posts hear though it seems i can lay directly onto the patio.

My question is this, will my highest spec i could find plan be any better than simply laying onto the patio?

My biggest concern was extending the lifetime of the decking and i figured by doing a "by the book job" i would be doing that.

Laying onto a patio concerns me regarding movement and dampness.

In my mind movement seems more likely without a significant sub-structure and movement means joints loosening and boards splitting lifting.

As for damp, wouldn't laying joists straight onto a weed resistant sheet allow water to remain in/on the sheet giving direct and prolonged contact with joist therefore increasing potential for water damage.

So what do you all reckon? Short cuts or not.

Also i am using a composite board and although it is expensive it looks the dogs. I have some samples. The firm is called Timbertech.
Has anyone used composite boards or Timbertech before?
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Save your back, lay onto the patio, If the patio has adequate drainage then it will be fine. You can always raise the frame level up slightly using paving slabs. Use pressure treated timber and treat all the cut ends.

No idea about the composite, I don't see that it's worth the expense (how much is it?)
I'd rather spend the extra on a hardwood deck.
what height is the deck going to be at above the existing ground level?
Only time you really need to consider doing it by the book ... Posts, Beams, Joists etc etc. is if it needs to be structurally sound, generally because it is over a few feet high.

This is probably why Thermo has asked for height above the ground.
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correct, although its more a case of common sense than the book. there is no point ripping something out that will produce exactly the same result as that which is being put in. it does depend on the height though
Hi and many thanks for your replies.

If i follow Deluks advice and use slabs to slightly elevate the joists (to combat damp i guess) then with joists at 2x6 and board at 25mm the total height will be 8 1/2 inches above existing patio height.
However having just read the brochures from the composite company i should have at least 12" between ground and decking board. So looks like it will have to be 12"

As far as the decision to go with composite Deluks, it was made with the fact that the composite boards require no maintenance and carry a 25 year guarantee. These points are important as my mother is of an age and condition where she cannot complete the yearly re-treatment of the decking. I am off to Ireland in the near future so i cant guarantee to be available to do the work for her. I guess even hardwood decking would need yearly treatment?
The boards cost £26 +VAT for a 3.2m length. Yes very expensive but they look like real wood so much so only a very close hands and knees inspection would reveal the truth but even my girlfriend and brother didn't realise the samples weren't wood. With no maintenance it seems worth the extra £1500.00 (roughly just over a pound a day over the 25 year guarantee period)

So i gather the extra slabs will alleviate my worries over water damage (excuse my paranoia but that gives me more concern about movement)and the potential for more movement without a substantial sub frame is ... negligable or of no concern? Am i reading you all correctly?

My main concern is giving the sub frame as much chance as the composite of reaching 25years service or is this just not possible.

Again many thanks what a diamond site.
Wood rots predominantly via the end grain so make sure you protect the ends of the real wood well.

Will it last 25 years though ... Not in my experience.

Does it need to ... Not in my experience :LOL:
if those boards can go without any maintenance it will be a miracle. they will still collect grime etc and need some cleaning/brushing down.
Yes sorry you are right cleaning is obviously a part of maintenance but a small jetwash should do the job.
goosergus said:
With no maintenance it seems worth the extra £1500.00 (roughly just over a pound a day over the 25 year guarantee period)

I make it 86p a week. Anyway, like you say, the subframe and whatnot will have an effect on it's lifespan.

I feel that I have to (respectfully) ask this question, given your description "mother is of an age and condition" will she still be living there in 25 years to enjoy your extra expense?
Surely that extra money could be put aside (high interest account!) and used to pay a handyman/gardener/family friend to go round once a year to wash down and oil the deck. You'd probably get away with every 2 years with hardwood.

Hardwood decking could cost as low as £2.50 a metre.
Well thanks for the help everyone but it looks as if i have to build the deck as i originally planned because of the twelve inch clearance requirement.

My mother is keen on the composite and i agree with her. Its not so much her age thats the problem but a disability she suffers.

As for the maths, right calculation wrong word. Swap day for week Around 1.15 a week more based on the extra cost over 25 years.

I supose much of the credit i give to the 25 year guarantee is that it proves a quality product not so much that it or my mother will be there in 25 years. Something that has 25 years life will still be looking good after 10 years and without much maintenance.

Anyhow, again i thank you all for your input

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