In the last few years, we’ve sanded more floors than I care to remember.
We turned yucky laminate covered floors into gorgeous sanded floorboards and transformed our dull and grey parquet into a luscious and rich oak floor.
We really couldn’t be happier with how our floors turned out but we did make some floor sanding mistakes along the way. We learned the hard way that there are things you should and shouldn’t do and, more importantly, there are things you can do to make your floor sanding experience much easier.
As we see some floor sanding mistakes over and over again, we’re sharing our tips and tricks to not only make your life easier but also help you avoid the floor sanding mistakes we made.
We made the mistakes so that you don’t have to!
1. Using The Wrong Grit Sandpaper
The by far biggest mistake I see is not using the right grit paper. I honestly can’t stress enough how important it is and you really won’t do yourselves a favour if you start to sand with paper that’s too fine.
What grit you start with will depend on what your floorboards are like. If they’ve been sanded before and just need a refresh you’ll be able to start sanding with finer paper but in most cases, you’ll have to start with a much more corse paper than you expect.
If your floors haven’t been sanded before, the maximum grit paper you should start sanding with is 24 grit. I know that sounds super corse and radical but anything finer will not sand away enough of the dirt and old varnish.
More importantly, though, it’ll cause you much more work not to mention cost as you’ll end up using way more paper than if you were using the right grit.
Our floors were slightly wavy and had a really thick layer of varnish on them so we started sanding with 16 grit paper!
Using the wrong grit (too fine) will also mean that your sandpaper clogs up really quickly. Clogged up paper is useless so it’s something you’ll want to avoid. Not only because it’ll end up costing you more because you’ll constantly be replacing the paper but also because of the additional time it’ll take you to keep changing it.
2. Not Sanding Enough
There’s really no getting around it – sanding your floors is hard work and physically tiring. When you first start sanding you’ll almost instantly see a huge difference in your floor but once you’ve removed most of the varnish and dirt progress will seem so much slower.
Mostly, this is down to the floorboards not being completely flat which means that the drum of the floor sanding machine won’t be able to reach all areas of the floorboards in one go.
This means that you’ll often be left with shadows either at the edges of the floorboards (if the floorboards are concave) or in the middle of the floorboards (if the floorboards are convex).
Although you’re probably thinking that your floors look good enough to call them finished, try to resist the temptation to stop now – it’ll make all the difference, promise!
Sanding these last bits away is definitely the most frustrating part of the whole floor sanding process as progress will seem almost non-existent.
You really want to keep sanding until all marks and any shadows are completely removed.
You need to sand your floorboards until they look brand new, even if you’re staining the boards (unless they’re going to be black or painted). It’s what will make the difference between your finished floor looking amazing and professional or average and amateurish.
3. Not Sanding Diagonally
We didn’t sand diagonally the first few times we sanded our floors but we did in our new home and it’s something we’d definitely recommend doing.
It makes sanding your floors quicker as it’ll even out your floorboards making sanding quicker as you won’t be left with areas of the floorboards that are difficult to reach (which is the shadow problem I mentioned above).
We never thought of the sanded floors in our Edwardian house as uneven – and they weren’t really – but the difference to our newly sanded floors in our current home really surprised me. It’s difficult to describe and impossible to show on pictures but they somehow feel much flatter and more even.
4. Sanding The Edges
Sanding the edges of your room is a complete pain. It’s backbreaking work as you’ll find yourself hovering over the edging sander for hours on end. The good news is that you can sand the edges slightly less than the main surface – in fact, it’s a good idea to do so!
You should finish sanding the main area with 120 grit paper but for the edges, we’d recommend you stop at 80 grit. It’ll still be more than smooth enough and will save you time.
It is totally possible to sand with a fine grit but the problem (especially as a DIYer) is that you can quickly end up with scorch marks on your floor which can develop because of the high heat and friction generated between the sandpaper and your floor.
5. Not Changing The Sandpaper Often Enough
One of the biggest floor sanding mistakes we made when we sanded our floors the first time around was not changing the sandpaper often enough.
After a day or so, our floor sanding mistake dawned on us and as soon as we started to change the paper more frequently we were able to sand the floors much more quickly.
Yes, now you’re thinking I’d rather save some money as the sheets and disks are really expensive but trust me, once you’re sanding you’ll really want to spend as little as possible time doing it!
There’s nothing quite like standing back and admiring your finished floors and although we definitely moan about how much hard work it is, it’s also a project that’s easy to do and very rewarding!
If you’re thinking about sanding your floors, you can see our full guide on how to sand your floors and floorboards here.
Have you ever sanded your floors or are your thinking about doing it in your home? Have you ever made any big DIY mistakes or any of the floor sanding mistakes we made?
What varnish did you guys use??
We used varnish in our first home and oil in our second home. Both have advantages and disadvantages. We absolutely loved the oil we used though and highly recommend it as it held up really well and dried fast, too. This is the varnish we used.
Hope that helps, Matt!
Cx
Your floors turned out so good! I ended up having a local company come out to refinish and sand our hardwood floor in our music room since it was pretty bad, but I would love to try doing it myself in the rooms that don’t have as much damage. Did you end up using a stain after you sanded the floors? If you did, what color was it? Thanks for sharing this!
Thank you, Alex! It was hard work but soooo worth it! We didn’t use a stain on any of the sanded floors in our homes. They are all just the natural colour of the wood.
Cx
Thank you for this insightful and beneficial article! We are sanding our floors and have two black marks we can’t seem to remove! One is a marker from old furniture, and another is a black x marked on the floor from some type of paint. How do you remove those hard marks without causing the floor to be un-leveled?
You’re welcome, Joanne! Are you sanding your floors or are you just trying to remove the mark? If you’re sanding, I’d suggest sanding over the whole surface of the floor a few more times until the marks disappear. You’ll find that they won’t budge for a while and then all of a sudden will vanish. You can go over the odd spot more than others (I wouldn’t do this too often though) if you find you have a really stubborn mark but generally it’s best to sand the whole surface evenly. If you’re worried that the stain is really deep, I’d recommend trying to remove a bit of it by hand with a hand sander – just to see if it’s even possible or if it’s penetrated the floor too much. Ultimately, it’s an old floor, so if you can remove most of it, it may just add to the character of the room.
Cx
Just bought my first house and the quote for refinishing the floors was $3000- for a very small house! So my brother thought we could tackle it. I rented an orbital sander and yesterday we spent all day sanding. Our biggest problem has been the finish collecting and for in a gunk that sticks to the floor which we then have to go around and scrape off. We didn’t think to use a pre-cleaner before starting. He also started changing the pads more frequently which helped but it still happens. He used a belt sander in the past and didn’t have this issue, not sure if it’s the type of sander we are using that may make this more of an issue.
It sounds like you are using the wrong grit sandpaper, Gina. When you’re sanding away old paint or varnish the sanding disks clog up fairly quickly and using coarser grit sandpaper to start will help avoid the problem (although they will still clog up just not as quickly or as much).
Hope that helps!
Cx
Lots of useful tips – thanks! Just one question – by insulating underneath the floorboards, does that not prevent air circulation under the house? We’ve got airflow bricks around the outside of the house, and someone suggested that by insulating underneath the floorboards it might prevent airflow and consquently cause rot? I’d arthe have the natural look of not using slivers, but equally I don’t want to have drafts, or have the underfloor structure rot. Any advice much appreciated!
Yes, and yes. It’s really important to not block your airbricks and allow the air to flow to ensure that everything stays dry and won’t rot. Many people stick the insulation under the joists rather than between them. This means that there’s a big air gap where condensation can occur. Exactly how’s best to insulate your floors will depend on the exact construction of your house. I’d recommend getting some professional advice that’s specific to your home. As a very basic rule though, condensation will occur where hot and cold air meet, so you want to make sure that the inevitable moisture occurs somewhere were the moisture can’t damage your woodwork, etc and can drain away/dry thanks to the air brick ventilation.
Hope that makes sense!
Cx
I just tried sanding and staining my floors for the first time. When we sanded small pieces of black something would cake on the sanding pads in less than 2 minutes and make the pads ineffective. We were able to scrape off the “gunk” but it left marks in the floor. I tried staining and it turned out very uneven. Any advice for dealing with the “gunk”? Should we strip the floors before sanding??
That’s so annoying, Katie – I totally feel for you! It sounds like your floors may have been painted before and when you sand them the paint melts and clogs up the disks. We have a similar situation in our guest bedroom where the floor had been coated in a thick dark red paint. What grade of sandpaper are you using? the coarser the better for these kinds of situations. You could alternatively use a heat gun to strip the paint (if that’s what it is) but it would be a lot of work (always test for things like lead paint, too!). I personally would be tempted to very roughly strip the paint (just to remove the majority of the gunk) and then start sanding with some coarse paper before moving on to the finer grade.
Cx
Hi, thanks for this, very helpful!!
I was just wandering where you hired the different machines from, and if you would have any recommendations on which machines are good? ive been looking around and there seems to be quite a big range?
Thanks!
That’s a really good question as the quality of the machine can make a huge difference! You will generally find that the hire tools are a bit less powerful than the ones the professionals use but they still work amazingly well. For our first house, we hired the machines at a small local hire shop. In our current home, we also opted for a small independent hire shop as we tend to find that they give better advice and more tips and tricks for handling the machines they hire out. The machine we used the second time around was by a company called Lägler and, if you can get your hands on one, it’s what we’d recommend as it was super powerful and easy to use. Having said that, I wouldn’t worry too much about it as you’ll probably find that most machines will do the job. Just remember to change the paper regularly!
Cx
I’m definitely going to sand the floor boards and stain and varnish them. While your guide is very helpful the question of filling the gaps between the boards is not fully answered. I have gaps of between 4 and 7 millimetres and I’m unsure if these are big or small gaps? If these are gaps that are of a size that need filling, then what should I fill the gaps with? All advice is welcome. Thanks garyround0@gmail.com
It’s down to personal preference what you do with any gaps.
We insulated under our ground floor (which is something I’d recommend if you’re exposing your floorboards) and the gaps were fairly small so that there were no problems.
I personally wouldn’t advise on gaps over 5mm. You can fill the gaps with strips of wood that are glued into place before sanding or with a gap filler like this one.
I personally don’t like the look of large gaps which is why we took up all floorboards in our bedroom and moved them closer together so that there was one large gap that we filled with another floorboard.
Basically, there are a few options and the decision is up to you!
Cx
Everytime I think if a question you’ve already answered it across this and your other articles on sanding! So detailed and easy to understand. Thank you! We’re currently buying a victorian semi with wooden floors so am reading up and keep ending up back on your blog!
Haha, happy to hear that you keep finding your way back to us! I’m officially obsessed with sanding – it’s such a rewarding job (even if it’s tough at time).
We’ve definitely written more than a few posts about sanding floors and ever time we sand something we learn something new.
We’re actually putting together a full floor sanding guide so that all information is in one place. There are a few things we learned this time around that we’ve not even managed to share yet!
Cx
This is great! We have yucky red and blue carpet all over our house and with a dog I’d much rather have sweepable, wipeable wooden floors. Just need to get on with it. I’ll certainly bear all these tips in mind!
I totally admit that I don’t envy you but I promise that the hard work is worth it!
We shared a full guide on how to sand floors, maybe it’ll be helpful for when you do get round to your floors. https://www.littlehouseonthecorner.com/diy-guide-professionally-sand-wooden-floors-floorboards/
Good luck with your floors!
Cx