self build waterproof basement formwork membrane concrete rods

Threaded FRP rods and nuts - leave no holes through waterproof concrete.

frp threaded rod

frp threaded nut
  frp threaded rod

The rods are sliced off flush when they are finished with.

Traditionally and still, formwork carpenters use a steel threaded rod through plastic tubes to hold formwork together.

They can wind them up very tight and undo them easily.

When the formwork is struck they re-use the steel rods again and again.

But they leave holes formed by plastic tubes.

Holes in otherwise waterproof concrete is fairly ridiculous.
  dywidag leak   This is a threaded bar hole repair in Caltite waterproof concrete that did not work. Other similar leaks in this Cheshire footballer's new mansion with underground football pitch were behind plasterboard.

The most expensive projects are plagued with problems.
  1. It costs the sub contractor a lot of money to fill in hundreds of holes.

  2. It causes the main contractor a lot of worry - were any of the holes missed?

  3. It costs the client a huge headache in costs and delays when the building is ready but there is water coming in from behind the plasterboard. But where is the leak? How much plasterboard do you have to take down to find it?

Much simpler and cheaper, therefore, to use a single-use rod and nut that will be waterproof for all time, every time.

I regularly get calls from people about leaks in new basements. Last month (January 2018) an architect was telling me that his last basement project cost £1million and they were chasing leaks for a whole year.

Much easier and better to use FRP threaded rods costing £2.50 per m and nuts £1.50 each.

There are many variations how to use them.

If you want to use thin nuts inside to control the width of the wall, just cut about 6mm off a nut and put the thin part inside.

The 65mm or so of remaining nut will be more than strong enough outside.

What you can see in this photo is a course of timber formwork and the man working for this self builder in the Cotswolds is nailing down a bit of batten between rods because that forms his holes without drilling holes.

A 6mm piece has been cut off the ends of nuts to make thin nuts that are adjusted to the thickness of the wall concrete.

Then the next board will go straight on top.

The boards already up on the inside are screwed to a triangular brace that was screwed to the floor first.

The brace keeps everything upright and in the correct position. The thin nuts keep the wall the correct width.

The best formwork carpenters took years to learn how to use steel threaded rods successfully and they command £300 a day in some places. If you aren't that experienced you will have much more success with my formwork and fibreglass rods.
frp threaded rods

The most popular way to use nuts is just one nut on each end of the rod and to cut that off with a mini angle grinder and thin blade when the formwork comes down.

Rods. £2.50 per m.

Available mostly in 2m lengths. Also a few at 4m, 800mm and 600mm.

Nuts. £1.50 each.

07773 377087 or

But don't cut the rod and nut off too quickly.

Plan what you do next.

If you have a corbel to form, a concrete roof to pour, or anything else that would benefit if you already have a threaded rod cast securely in the wall below, use 2 nuts so that you can get them both off and use the threaded rod again.

2 frp nuts   reuse frp rods

These rods are stronger than steel in tension but they twist easily and the nuts are designed to bind on. That is why we use two nuts if we want to unscrew them or, more usually, chop them off.

frp threaded rod stronger than steel

stock frp rods stock frp nuts

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