Thread: How often can you sand back timber floor before you get to tongue?

Sounds like they would be sanding the finish off to apply a new finish rather than sanding down into the wood. I'd be inclined to pay the poor floor finisher a bit more if they have had to re-do it three times. It is not a highly profitable trade, it is hard dusty work with high costs for machines and sandpaper and varnishes. How could it need re-doing three times ?

Before comment, what type of finish is it and what is the problem with the finish, also what was the process and how many coats did each attempt get

Originally Posted by Giro1959

Hi, my newly installed 19 mm timber floor has had to be sanded back 3 times because of problems with the finish.
Does this reduce the life of the timber in terms of number of times I can sand back in the future ,And if so Should I be expected to pay full price for this floor ?
any advice?

It depends how much they have had to take off.
Problems with the finish usually only involve sanding back the finish and are unlikely to remove much timber.
Is there any way you can measure the thickness of the floor?

Originally Posted by Giro1959

Hi, my newly installed 19 mm timber floor has had to be sanded back 3 times because of problems with the finish.
Does this reduce the life of the timber in terms of number of times I can sand back in the future ,And if so Should I be expected to pay full price for this floor ?
any advice?

Just as a note of caution for the future (and rwbuild would have the authority here):
In a 19mm board you could expect the tongue to be about 6mm from the top. I would think that the bare minimum you would need is 3mm still above the tongue for the T&G to be able to hold securely (because nails slip with time). That would dictate an absolute maximum of 3mm could be sanded off the top, and probably a bit less. Less still, if it's softwood, like the stupid pine floor here.

Originally Posted by rwbuild

Before comment, what type of finish is it and what is the problem with the finish, also what was the process and how many coats did each attempt get

1st problem was grit & bubbles. This was 2 coats of polyurethane over a sealant.

2nd time it was rejection. Same finish.

3rd time finish was sealant, polyurethane coat and water based finish over that.

final result is better overall, no rejection issues but still have bubbles throughout

sanding must have penetrated timber as well as finish because nails became visible in some areas.

Originally Posted by Giro1959

1st problem was grit & bubbles. This was 2 coats of polyurethane over a sealant.

2nd time it was rejection. Same finish.

3rd time finish was sealant, polyurethane coat and water based finish over that.

final result is better overall, no rejection issues but still have bubbles throughout

sanding must have penetrated timber as well as finish because nails became visible in some areas.

1 more question before I comment, what species of timber is the flooring and how old or long as it been down

You should have 3mm or 2mm at the bare minimum above the tonguebefore the boards are “unsandable”....this though must be uniform across thefloor.
As to how many times, often it is not the coating that isthe issue but the sander. If you have someone that is heavy handed with a beltsander, the drum will take off more in parts...creating “chatter marks”.
The coatings do have to be removed and this always takes offpart of the timber as to how much depends on the coatings and how heavy theywere applied. If there was a rejection issue, the coating was not removedcompletely. This should be done, if or when a different coating is applied.Even when one applies the same coating later one, you need to ensure that thesurface is completely clean; often this is a light sand back with a screenback.
If you now have bubbles, then you need to find out why. If it was done recently, what area are you in?Was there heating in the home or freezing cold as in the eastern states?Coatings do not like the cold. Grit in the coating usually means the area wasn’tvacuumed prior to coating and or dust was blown into the area when the coatingwas wet.
As to the nails...this should be one of the first thingsdone, sink the nails and putty. This also ensures one does not hit the nailswith the drum which can ruin it long term. Also if the nails remain flush withthe surface, with movement (as houses do) the nails will just move to above thesurface and if you like walking in bare feet or have kids crawling, Ouch.
Is the person that did the floor a professional floorsander?

Good answer Angela.

What effect might the wrong type of abrasive on the belt sander have (stearate, non-stearate etc)?

Originally Posted by rwbuild

1 more question before I comment, what species of timber is the flooring and how old or long as it been down

brushbox, newly installed 4 months ago

Originally Posted by AngelaPetruzzi

You should have 3mm or 2mm at the bare minimum above the tonguebefore the boards are “unsandable”....this though must be uniform across thefloor.
As to how many times, often it is not the coating that isthe issue but the sander. If you have someone that is heavy handed with a beltsander, the drum will take off more in parts...creating “chatter marks”.
The coatings do have to be removed and this always takes offpart of the timber as to how much depends on the coatings and how heavy theywere applied. If there was a rejection issue, the coating was not removedcompletely. This should be done, if or when a different coating is applied.Even when one applies the same coating later one, you need to ensure that thesurface is completely clean; often this is a light sand back with a screenback.
If you now have bubbles, then you need to find out why. If it was done recently, what area are you in?Was there heating in the home or freezing cold as in the eastern states?Coatings do not like the cold. Grit in the coating usually means the area wasn’tvacuumed prior to coating and or dust was blown into the area when the coatingwas wet.
As to the nails...this should be one of the first thingsdone, sink the nails and putty. This also ensures one does not hit the nailswith the drum which can ruin it long term. Also if the nails remain flush withthe surface, with movement (as houses do) the nails will just move to above thesurface and if you like walking in bare feet or have kids crawling, Ouch.
Is the person that did the floor a professional floorsander?

Thankyou Angela, my main concern with this issue is that I have had my newly installed timber floor sanded back 3 times already before I have moved in.Therfore when I need to resand in the future which I inevitably will have to at some time, I will be limited as to the number of times I can do so because they have already been sanded back so often as new.
And if this is the case, should I be expected to pay full price for this timber floor if its life has been shortenend by so many sandings already?
I'm merely looking for advice and other people's views on the matter.

OK, the flooring is 19mm thick when first nailed down, assumming the first sanding would have taken approx 0.5mm, the 2nd about 1mm to get rid of the first finish and the 3rd 1mm, that would leave 17.5mm at worst 17mm which is ok for a hardwood floor and also explains the nails being sanded again. I suspect you have end matched flooring that is the boards have a T&G on each end which allows you to join them anywhere and not limited to over a joist.

The question of poor finish is caused by:

Poor preparation ie no vacuuming to remove dust etc
Rushed application of sealing coat and not uniform
Very high humidity on days when done
Never mix different types of finish
2nd / final coat applied too soon after sealer coat
Nails should be 2 to 3 mm below the surface minimum

You may have an air flow, ventilation issue under the floor, chech for clearance at lowest point should be minimum 400mm from ground to under bearer, also check that there is no pondage of water under the house as well

You will be able to sand another 1.5mm max off the floor before you start to get trafficable deflection in the boards.

Hope it has been helpful FenceFurniture.
Some machines use the endless belts, that is the ones that Ithink you mean by non serrated. The serrated ones, depending on the floor, the coating or howfussy the sander is, may leave chatter marks when this part comes in contactwith the floor. It also depends on what belt sander one has. From my point ofview, it is more economical to spend a few extra dollars on materials in thebeginning as this save heaps of time and gives a better finish. Often, cheaperproducts equal false economy.
Starting with the wrong grit though is the same. If the surfaceis very rough or there is a heavy coating that needs to come off, use a roughergrit from the beginning and work upwards to the finer grit. This is quicker andsaves time using more of the finer grit papers is just a waste and timeconsuming.
Giro1959
“Sanded back three times due to a problem with the finish”.As to should you pay I think depends on a number of issues and it may be bestto get an independent person in to assess....this though can open up anothercan of worms. Did you take photos of all coatings and issues?
Firstly, the product used, was it applied as perspecification from manufacturer? This takes into account some of the pointsrwbuild mentions.
Did the applicator know how to use it? Did he take intoaccount some other points mentioned above?
With any jobs, private or otherwise, stuff happens...but Iwould have thought 3 times would be too many times. What does your applicatorhave to say?
Insert a metal ruler into a space and see how much timber isabove the tongue. Do it in a number of areas, this will dictate if or how manytimes you can sand the surface back.
Would I pay? Not until I would get some really good answers as to why 3 times.

Hi Angela, funnily enough (fro me) it wasn't a tpyo - I meant Stearate. Some abrasives are Stearate coated which can interfere with finishes, so I was wondering if that might be a factor.

Correct me if I am wrong isn’t the coating to stop thepapers clogging up as quickly?
If it was interfering with coatings, I would think the manufacturerswould have some sort of warning not touse these papers. I can’t see how the surface would be effected that it wouldcause some sort of contamination with coatings though.