How to widen gaps on a deck?

[TommyTorquay]

I have 70 square meters of silver top decking that has been down 10 years.  The gaps between the boards have now swollen together and/or have debris embedded.  I have attempted to use a circular saw free hand to re-widen the gap, but I am not steady enough to do the very long cuts required (some up to 10 meters in length).

Can anyone suggest the best way/tools to move forward on this project?

[EricL]

Hello @TommyTorquay 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your decking boards.

If you are planning on rejuvenating your deck, I propose seriously thinking about relaying your decking panels and putting in the maximum gap of 5mm between panels. While the decking panels are off, I recommend hiring a planning machine and trimming the surface of the panels. This will give your deck a fresh new installed look and allow you to stain and seal it with your preferred colour. I feel that you will not get a satisfactory finish if you were to just cut the panels to crate the gaps.

Let me call on our experienced members @Dave-1, @Nailbag, @AlanM52 and @Noyade for their recommendations.

If you need further assistance, please let us know.

Eric

[Nailbag]

Hi @TommyTorquay 

Silver-top Ash decking boards are typically a very good quality timber to use for decking. The fact they have swollen that much is very surprising, because even without oiling I would expect them to shrink slightly with age. Unlike treated pine which would expand.

That said, if the boards are now meeting on their edges, then sounds like the gaps were minimal to begin with. And where the gaps haven't moved and there is debris in-between, thats normal for any deck. The debris will always rest on the exposed joists. Regular cleaning with a hose and when re-oiling rectifies that.

If the overall scenario of the deck is that mostly the boards are bind together, then the best solution would be to remove them all and re-lay them with a suitable gap as @EricL mentioned. But unless the tops of the boards are in extremely poor condition, I would avoid running them through a thicknesser.

If this isn't viable, using a straight edge as a guide with your circular say set to 19mm depth (thickness of a board) will at least provide straighter cuts. But depending on your blade, it's only going to give you around a 2.5mm gap. The danger here to consider, that if the saw blade pinches it could kickback across the top of the board deeply damaging it. You also need to be positioned offset to ensure your own safety. Setting correct depth and using a blade in good condition will reduce this possibility. The other consideration is cosmetically the board will loose the soft round edges to a squared off one which will spoil the over all look, especially if not all the boards are done. In short, this is not the solution I would be recommending.

Questions:

Are they and have they been regularly oiled?

And can you please send through a few photos wide of the deck lengthwise and closer on the issues and how you have been cutting them?

Nailbag

[Dave-1]

Good morning @TommyTorquay 

I was wondering if you could supply a few pics of the deck?

One of the deck overall and maybe a few showing the boards coming together/debris type deal?

When I rejuvinated my deck I actually went around teh whole lot with a hacksaw blad to clear all the debris. There was a lot of dirt, sticks and leaves between the boards. (I have a lot of trees about) Once I cleaned the valleys the timber hadnt moved in the years I since I have installed it. It was time consuming but maintence wise something I know I should do more often. I think my timber was yellowgum (not bought brom Bunnings, just a local supplier)

If the gap is still too tight after attempting to clear the valleys then the next option is towards @EricL's suggestion and trying to pull up boards that have been there for a long period is not fun. Mainly due to the fixing nails/screws locking in place.

Dave

[TommyTorquay]

My bad, but they were laid and left natural when we built the house.   Taking up the entire 70 square meter deck without damaging the boards, then planing the boards and relaying it is way beyond what I can or want to do.

Since posting this, I have looked all over the internet for solutions. There is a company in the US that has come up with a saw guide that is specifically designed to fit on the bottom of the circular saw for doing this job.  Basically, it is a plate that attaches to the bottom of the saw plate that has two fins (one at the front and one at the back of the plate) that fit in the gap and keeps the saw straight as you are cutting. So I am ordering that.

As far as using the circular saw to widen the gaps, I will put two saw blades together on the saw.  This will give me the 5mm you recommend.

Thanks again. I really do appreciate your advice.

[TommyTorquay]

Thanks Dave.  Have a look at my reply to Nailbag. I have also uploaded some photos.

[TommyTorquay]

Thanks Eric.  Have a look at my reply to Nailbag. I have also uploaded some photos of the deck.

[JacobZ]

Hi @TommyTorquay,

It sounds like a fair solution to the problem, but I would not suggest stacking circular saw blades. 

Dado blades, which are designed for this purpose, are only designed for use with table saws.

I am not aware of any circular saw manufacturer that would be comfortable with this setup, and I would be extremely wary of going outside of their recommendations. The potential for issues is far too great to be worth the risk.

You would be much better off making two separate cuts.

Please remember to put your safety at the forefront of any work and wear eye protection, hearing protection, a mask, gloves and long protective clothing.

Jacob

[AlanM52]

Hi @TommyTorquay,

.Lots of good advice and here are some of my thoughts mixed in with what's been said.

We need to figure out a way to do the gap thing without relaying the decking.

@Dave-1 mentioned pulling up decking (and relaying) is not fun and I say it's a PIA.

The last time I did that helping a friend (screwed decking) on the way home I was mumbling to myself - never again.

We have never lived in a house with timber decking but I have suggested to others try using a handsaw and now I'm thinking a plunge saw.

That's heavy work for a small motor so would need to be done in sessions and in my case I would sit on a small stool with castors.

You could restore some of the rounding (at least clean-up) by running a 1/3 sander along the edges.

Cheers