Make or Break
David Gatfield, Technical Services Manager at flooring and walling manufacturer, Altro, looks at welding – the problems that can occur and how to make sure you get it right the first time.
Picture the scenario, you’re working on the refurbishment of a large school, there’s no 240v power and the lighting is temporary but there’s plenty of it and you can clearly see what you’re doing. You’ve just spent two days ripping up an old floor and have even gone to the trouble of scraping and grinding away the old adhesive, and have applied a good coat of primer before laying a nominal 3mm of quality latex screed.
The following day you grind the latex and then apply a tight coat of feather finish - a beautifully prepared floor ready to receive the expensive sheet flooring. The installation goes well and all individual sheets of material are scribed into the wall and neatly fitted around all the door frames, the adhesive is spread and the flooring laid into it and rolled with the regulation size roller.
You stand back to admire the installation and give yourself a deserved pat on the back. All that’s left to do is the welding and the job will be finished and you can get it invoiced. As it’s Friday afternoon and you want the adhesive to cure first, you decide to weld it on Monday morning.
When you get to site Monday, a bit late because of traffic and dropping the kids off at school, you find a couple of joiners have set up shop in the room you’re working in and the floor is already covered in wood shavings. Sound familiar?
Anyway you “politely” remonstrate with them and the area is cleared to enable you to get on with the welding. Unfortunately they’ve taken the temporary lighting with them out of spite and you’re left to finish the job in semi darkness in this windowless room. Still it’s only a bit of welding, isn’t it?
You groove the joints and they look ok so you weld everything up, sweep up the bits of weld you’ve cut off, have a quick squint around the room in the dim light and off you go to the next job.
A week later the power is on and you’re dimly lit room now has more lighting than universal studios. The contract cleaners are in getting the school ready for the grand reopening, they pick at a bit of weld sticking up at one end of the main joint and out it comes. The alarm is sounded and before long everybody and his dog is tugging at welds and picking at edges looking for problems.
OK, the above is a work of fiction, but have we not all been there? I know I have. Welding, though a small part of the total job is arguably the most important part of the fine detail of any sheet flooring installation. Get it right and the job looks great, get it wrong and often the only option is to rip everything up and start again at great expense – yours.
The welding of coated products or those with a wear layer sometimes gives cause for concern, particularly if you’re using them for the first time. But there is little or no difference in the welding process when using these products provided you follow a few basic rules. Which leads me nicely into my unofficial Altro guide to the welding of sheet pvc flooring.
- Form a neat tight joint between adjacent sheets of floorcovering.
- Allow adhesive to cure overnight where possible.
- Groove the material to the correct depth (approximately 66% or 2/3rds the thickness of the flooring) Where coated products have been coved it’s important to groove the internal angle prior to hot welding.
- Set the welding gun to the required temperature (about 350 degrees) if in doubt trial the gun on a piece of scrap material before attacking the main seams.
- Weld at a steady consistent speed, too fast and the weld won’t take, too slow and you may burn the flooring.
- Allow the weld to cool before trimming.
- Trim the weld flush with the floorcovering.
- Don’t work in the dark.
I hope these points will help you to improve your welding and remember that the quality of the installation is only as good as the quality of the welding.
This article first appeared in the September 2010 edition of the CFJ.