Are gaps absolutely necessary on decking?

Grizzlybare

I am finally installing the composite decking without a tried and true design. The dimensions were such that we either had to leave a 5 1/2" board out that caused a .3" gap or pinch them together where there is no gap at all. My wife loves the look and the smoothness of no gap in the composite. I understand that there could be some expansion, but if the boards are installed in the hottest temp, when would they expand greater? It would seem that they would draw up from that installation rather than expand.

Wife likes the idea of walking on it with heels and not worrying about going through or the deck chairs catching on the gaps, etc.

Without even the slightest gap, there should be no leaves or other residue in the cracks and what does settle there I would think would wash out with a pressure washer on low pressure. It does look much cleaner without the gap.

We have put on the border and the boards are very snug but have not been screwed down yet.

Another issue is that we are unable to get the stainless steel screws to go into the composite material without a 1/8" pilot hole. Is that normal? It will take much longer that way than if we could just drive the screws into the decking.

Thanks!

SuperHans

Follow the manufacturer's recommendation for the spacing. In addition to expansion issues, if you snug all the boards up you won't have proper drainage and water will pool all over.

kwikfishron

As mentioned follow the manufactures instructions exactly.

If you don’t you will likely void the warranty, something you just may need with your composite decking.

__________________

coderguy

If you can, get two drills. Have someone drilling pilot ahead of the person drilling screws. You want the deck to last forever and be low maintenance - so do pilot holes and space the boards. She can't walk on the deck at all if it is always slippery and wet.

Tom Struble

hmm no gap? i wonder why no one ever tried that before?

Daniel Holzman

Expansion of wood products (this includes composite material with significant wood content) is generally controlled by moisture content of the product, not by temperature. Wood typically expands across the grain by anywhere from 1 to 3 percent, depending on species, as it goes from driest condition (typically 6 percent moisture content) to wettest condition (typically at least 30 percent moisture content).

Composite materials that use sawdust or wood fibers in the core are subject to expansion and contraction due to changes in moisture content, which is typically seasonal. In order to prevent buckling of the deck during the wet season, you need adequate gaps between the boards. The manufacturer (as noted by other posters) will typically tell you the required gap between boards. Bear in mind that if you install the deck boards when they are dry (this is typical), they are going to expand after a few good rains. Your wife will not enjoy walking on a deck that feels wavy.

gregzoll

Actually instead of screws into the deck boards, I would use hidden fasteners. Not only is it more aesthetic to the eye, but will keep a small gap. I think that the OP is afraid of the situation, where those parties that do not follow instructions, use a piece of decking laid on side for the gap, which is incorrect, but they do it to save on materials. Less materials used, more money for something else.

Grizzlybare

Well, now that presents a problem. The spacing will have to be over a 1/4" for the boards to come out uniformly. I have a 19 board run that is snug. If the boards are 5 1/2", taking one out will leave me 18 gaps at .3" per gap. Is that adequate or too much?

Willie T

This is usually decided for you by the fact that the house (assuming you are starting at the house edge) is rarely square with the outer edge of the deck.

What is generally done is that the 'starter' piece against the house is ripped down narrower on the backside so that it both fits to the house, and also leaves the side that will match the next board installed parallel with the outside edge of the deck. (same distance away, all across)

This way, you will end up using 19 pieces with a reasonable gap. It will no longer be tight because you ripped out some of that 'starter' board.

__________________
"True eloquence consists in saying all that is necessary, and only that which is."
François Duc de La Rochefoucauld
Willie T

antlerdancer

What I have found helpful on all the decks I have built is I start at the outside edge and work toward the house.That way all the planks are consistant width and all gaps are equal.Then I rip the last board down to fit the house,gap included.Also,the hidden fastener way,IMO,is the only way,if possible.

coderguy

I assume these are what you guys are talking about?

http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

Didn't know; changes everything!

I notice some of these (I linked one with them on purpose); have spacers on them... nice way to get an even spave every time; or are they annoying? I know they sell them without the spacer clip...

gregzoll

You would need something in the lines of a biscuit joiner to make the cuts. They make some with teeth in them, so you do not have to use a biscuit joiner.

antlerdancer

The ones I used were 8ft strips almost like cornerbead,but with alot more substance.I dont remember brand but got them at Menards

Grizzlybare

It is looking great. Wish the screwing was a bit quicker. Very time consuming and back breaking.

By the way, I took a metal strip and bent one end, measured the proper width for the pilot holes and drilled them into the metal strip. Then by placing the bent edge on each of the boards the holes lined up in the right place and all the holes are uniform in each board. The strip was a "U" shape and was about 3/4" wide. With the holes drilled in the center and lined the strip along the joists. On the end of the boards, the edge of the strip aligned with the end of the boards and the holes came out perfectly spaced at about 3/8" from the end.

Grizzlybare

Next question.

As I come to the end of the deck, I am faced with many options as far as length of boards. As the deck is some 40' long, I started with a layout pattern of

4'
12'
8'
16'
4'
12'
8'
16

I have an angle corner on the end that makes the deck boards all dif lengths and some will be very short. Is 48"' the shortest board length I should have, 32"?