Decking plan - so many options - please help

27 May 2013
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United Kingdom
I realise there must be a post regarding decking frame planning every other week on here but I am hoping you could indulge me before I go insane.

I have been planning a 8.2m x 4m decking project for what feels like a lifetime and I am so worried I am over engieneering things I thought I would post here.

The deck area is rectangular-ish and is a raised deck (but only slightly) which extends out 8m from the back of the house and 4m in width. Here is an image:

Essentially I have a number of 4x4 posts at 1.5m intervals.

Running vertically (as looking at the plan) I have a 4 rows of 2x6 pairs which are bolted to the posts

Now my plan was to then use these beams as bearers and have the 4x2 joist framework sitting on top of these 2x6 support beams. Then obviously have the deck boards running vertically from the back of the house and out.

Is this over-engineered?? I desperately need to know.

Having looked at about a thousand web sites the closest I have come to making this more simple is to simply attach cut-down joists at 400mm centres 'in between' the 2x6 beams. Does that make sense? In other words the joist would be attached (screws or hangers) by butting up to the 2x6 beams. This would mean that instead of having 4m joists running on top of the beams and horizontal to the house I would have roughly 2, 2 metre joists slotted between the beams - running horizontal to the house.

The only thing I am pretty much fixed on is that I will be using posts to support everything. It's the framework that is really confusing me.

I know having a 3 tier system (bearers, joists and decking) is the most rigid method of doing this but is it overkill?

BTW- The bearers would only be hovering 2 inches off the floor.

I really hope someone can help. Thanks for reading.
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its a good layout engineering wise
if this was in area of design...the columns would have the joists vertical and horizontal members bolted into the webs.

as this is wood i dont think hangers are really the answer and seem fiddly

you have two bearer running this for strength or bearing...if for bearing only you only need one and make the horizonal deck bearers continous over the inner supports

i like you tend to overkill a job so i might be down strengthening the idea

generally you take floor loading and work out the simply supported bending moment on the vertical spans and then check out the bending stress and deflections/shear

no one wants a bendy deck so i reckon inch by thick is the way to go

if you have the money and time do it!!

as for the gap under the would seem ok if air can circulate and you treat the undersides which are in tension and the weakest part of the bending


someday they will do a click post and bearer system in aluminium and then we wont have this problem...

Thanks for the reply mrcrow.
I have to confess though that I only only understood a small part of it. I'm afraid I am not in any way technical and am only undertaking this as a foolish attempt to impress the wife :D

The main reason I drew up this plan was because it reflects an approach that I found online. This approach was a clear step by step approach form a U.S. online video series. From the conversations I have had it tends to be the U.S. videos that really do come up with the unbelievably strong structures. As they do have areas that face extreme weather I can see why.

What I would like to do is to simplify mine if possible and, therefore, reduce my timber requirement/cost.

Would the approach below work? In it I am putting everything on one level. I think this is called flush beams or flush joists. Well, flush something!

Essentially the entire joist framework will be attached to the posts and not resting on top of the beam bearers. In this scenario the joists are cut and fitted flush either side of the central support beam. I have used weird square bracket symbols to suggest that they are attached with hangers or screws.

Is this any less engineered?

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brill..just like the floor of a steel building at the top out level

as for the american approach to things
look at their cars, roads, refrigerators and vacuum cleaners etc

its a big country with loads of room and so they make the best of it

i lived there btw


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