In today’s modern working world more and more jobs revolve around sitting at a computer or at a desk for sometimes quite long hours.
Recently, many chronic health conditions such as heart disease, diabetes, cancers and other conditions have been linked to this practice. One other condition associated with this is back pain.
Sitting in an uncomfortable for badly supporting chair can put pressure on parts of your spine and lower back and overtime this causes pain and other debilitating conditions.
With this in mind, it is essential that if you do have to sit stationery for hours on end that you use a comfy and fully supported seat.
What’s the Problem With Office Chairs?
There’s nothing necessarily wrong with the many office chairs available on the market today, many of them are very good but as we are all things you get what you pay for.
Some of the cheapest office seating available doesn’t provide adequate support and after a while can become very uncomfortable and start to cause serious issues.
On the other hand however the more expensive office chairs do offer fantastic support and prevent unnecessary pressure on your back and other parts of your body and help to promote great posture that all limit the effects on your health.
If you’ve ever looked into the various types of office chair available then you may have come across the term ergonomic. This essentially means that the chair in question has been designed primarily for comfort and to help alleviate unnecessary pressure on parts of your body lead to debilitating health issues.
Regardless of what type of office chair you have the age of your chair is also a factor.
Even the best quality chairs will wear over time, sponge padding will become compressed, lumbar supports will lose their support and you are then at risk of causing yourself and injury if you continue to use them.
One other issue with office chairs is that the actual seat is supported by a post and when the foam supported the seat starts to go your entire body weight bears down onto the post causing a great amount of pressure in your lower back and bottom.
So, is there a solution to this?
The first and most obvious solution to this is to buy a new chair but with decent quality ergonomic chairs costing upwards of £200 this isn’t always an option.
When we were thinking over this issue due to the fact a few of our own office chairs coming to the end of their life and getting rather uncomfy we were thinking; what are the most comfortable chairs for the most reasonable cost?
After deliberating for a while we suddenly thought about car seats. They offer great, all-round support, many have adjustable lumbar support and also, more importantly, have sprung bases.
Car seats are specifically designed to be comfortable and provide great support over long periods of time, not only to ensure the occupant is comfortable while driving but also to provide support during an accident.
The Padding and foam used in a car seat is quite often thicker, more durable and of better quality than that used in a standard office chair.
With this in mind we decided to test out this theory by building an office chair out of a car seat, read on below to find out how.
What Type of Car Seat Should I use for an Office Chair?
During our search for the ideal car seat to use for our office chair we looked at many different types of seats and designs.
Due to the many different designs and types of car each set of seats is designed specifically to fit into that particular car, in some cases around bulges in the bodywork, transmission tunnels and other obstacles.
Also, the bases of many seats are set at different pitches, some being flat and some that slope towards the back of the seat lifting your knees up.
After looking at all these different layouts and designs we found that the best type of car seat to use is one that features a flat set of runners that bolt to a flat level floor pan.
Ideally, if you can also find a seat that has a flat base this is also preferable but if not then you can compensate for this in the design as we have below.
Additionally if you can also find a car seat that has adjustable lumbar support this is an added bonus and will allow you to further fine tune you’re perfect seating arrangement.
While selecting the ideal seat for you obviously make sure you sit in it and test how comfortable it actually is and also check underneath to make sure that it is sprung. On the whole, sprung seats tend to be more comfortable than those that just feature foam on a steel base.
After searching through numerous scrap yards and sitting in and inspecting a great many different car seats, the seat we settled on was from a 2006 Saab 93.
Safety Concerns Using a Car Seat as an Office Chair
This may seem like quite an odd statement but if you have looked a fair few modern car seats you may notice that the majority have airbags built in to the sides of them.
This is obviously quite a concern as essentially you have a small explosive device in the side of your chair. Although they are designed to deflect an explosion and any debris away from the occupant this obviously doesn’t mean that it doesn’t pose a risk to anyone at the side of it.
With this in mind if you can find a car seat without side airbags this is the way to go, but if not contact a local mechanic or the manufacturer of the car seat and ask them to disarm and remove it for you. Better still try to find a car seat that doesn’t feature an air bag.
How to Build an Office Chair From an Old Car Seat
Now that you have selected the ideal car seat for you it’s time to start constructing your office chair.
Strip Down the Car Seat
First job to do it strip off all the unnecessary gubbins from your car seat.
Sit the car seat up on a bench, Work Mate or other flat surface and have a close look at the underside. Using a pair of wire snips start by cutting away all the unnecessary wiring. Many modern car seats have heating elements, electric adjusters etc. that we don’t need in this instance so they can all be removed.
Once all the wiring has been removed you can then unbolt runners and anything else that we’re not going to need in this instance.
Constructing the Office Chair Base
To construct the base for our office chair we are going to use a simple “X” type design. Essentially this is 2 timbers joined across each other at 90 degrees using a halving joint.
First, cut two timbers to 650mm in length then measure and mark the centre of each. Once marked draw line across the timber using a carpenters square to define the centre point.
Next, measure the width of each timber, this case as for using 4 x 2 timbers each timber should be 4 inches wide but in actuality each timber is 90 mm wide.
Using a tape measure, mark 45mm either side of the centre line you just created and again use your carpenter square to mark a line across the timber. Repeat this for the other timber also.
Next measure the depth of one of the timbers. It should be 2 inches but in actuality, as before it’s only 42mm.
Using a tape measure, measure down and mark 21 mm from either line either side of your centre line and then draw a line between these two marks. This now defines how much we need to cut away in order to clear or having joint.
Using a mitre saw (if you don’t have one you can use a hand saw and a chisel) set the cutting depth of the saw to 21mm, cutaway the unwanted timber ensuring you cut inside the marking lines to create a nice tight joint.
Once the first timbers done repeat this for the second then tidy up both joints using a sharp chisel and some 80 grit sandpaper.
The final job to do with the base before joining it altogether is to mitre the ends of each of the timbers. This is simply an aesthetic thing and looks a little nicer than a square end.
Once done position the joints together and test the fit, it should be quite tight. Before knocking them together fully apply a good amount of timber glue to both joints and once done position them back together and knock them together using a hammer and the scrap piece of wood as a drift to prevent any damage.
Simply screwing our support upright to the base isn’t going to cut it in this instance as once someone is sat in the seat and moving around and swaying this is going to put a lot of pressure on the point that the upright is joined to the base and just using screws won’t be strong enough as this movement will cause them to slacken overtime.
To compensate for this we are going to make a dowel that will run through the base and up into the upright support. This will take some of the pressure off of the screws and create a much stronger joint.
To make our dowel we are going to use a length of old broom handle. Cut two 80mm lengths of the broom handle and then sand down the cut edges so that there are no burrs that could affect the fit.
Next, using a tape measure the diameter of the piece of broom handle then select a flat drill bit or auger bit of the same size.
Now, mark the exact centre of your base by drawing a cross through the point where the two timbers join. Pop the flat bit or auger bit into your drill and drill a hole through this point. As you drill make sure you hold your drill totally upright so that you get a square hole.
Pop the dowel in to test fit it, it should be a perfect fit but if not then sand the dowel down until it fits.
Before we fit the dowel in place fully, using orbital sander, sand the entire base down so that is smooth and there are no rough or sharp edges have. If you don’t have an orbital sander a piece of 80 grit sandpaper on a sanding block will do just as well.
Once fully sanded, spread some wood glue in the hole and over the dowel and push it into place. Put it to one side for a good few hours to fully dry.
Construct the Mounting Base for the Car Seat to Sit on
The type of base we’re going to construct will very much depend on the type of car seat you’re using. If your car seat sits flat no problems, you can simply construct flat base.
However, if your car seats slants in the same way that the one we are using does we’re going to need to construct the base that levels this up.
Firstly, we need to figure out how much we need to level up the seat by. To do this, lay a spirit level on the front of the seat (the highest bit) and run it to the back so that it touches the seat back.
Adjust the spirit level and level it up and then use a tape measure to measure from the base of the level down to the top of the seat. This is how much we need to level up the seat by, in our case is 90mm.
As this is quite a sizeable amount to level up the seat by we’re going to need to use some fairly substantial timbers, in this case 6×2 timbers.
Next, measure the distance between the front and back mounts on the base of the seat. In the case of our seats this was 390mm. Cut two pieces of 6×2 timber to this length.
Take one of the pieces of timber and lay it down on a work surface. Using a tape measure, measure down 90 mm on the front edge and make a mark and then use a straight edge to draw line between this mark and the very top corner of the opposing side. Repeat this for the other timber also.
Using a hand saw or a bench saw cut through the line on each piece of timber and you should then be left the two angled pieces of timber that will successfully level up our car seat.
Use an orbital sander or piece of sandpaper and a sanding block, fully sand down both pieces of timber, removing any sharp, acute edges.
Now, measure from the back edge of the rear mounting bracket on the seat to roughly the centre of the first third of the seat. For our example here, this is 140mm. This is so that we can position the upright support timber directly under the part of the seat that will take the most weight.
Take one of your mounting timbers and measure in from the back edge 140mm make and mark and then use a carpenter square to mark a vertical line at this point.
Recalling the measurement of our piece of 4 x 2 timber earlier, 90mm, measure and mark 45mm either side of the vertical line you just marked using your carpenters square to make 2 further vertical lines at these two points.
Measure and mark 42mm up both of these lines and then draw a further line between the two points.
Using a mitre saw with the cutting depth set 42mm or a hand saw, cut away timber from this area then tidy it up using a sharp chisel and a piece of 80 grit sandpaper.
Using a tape measure, measure the width between the two front mounting points on the base of the car seat then cut a piece of 4 x 2 timber to this size. In our case this was again at 390mm.
Measure and mark the very centre of this timber and then measure and mark two points 50mm either side and then draw 2 vertical lines.
Using a router and a cutting out bit, chop out the timber between the lines to a depth of around 8mm. This recess rely the centre post to say snuggly in and prevent too much movement. If you don’t have a router then this can be done using a hammer and a sharp chisel.
Once done, fully sand the piece of timber down including the recessed area you just created.
Next, take your two mounting timbers and place them with the slanted edge face down on a work surface. Take the cross piece timber you just made and set each end into each recess on the mounting timbers and test of fit, it should be fairly tight. Just before you knock them in all the way, take the timber out and coat the inside of each recess with wood glue.
Once coated, knock the cross piece timber back in using a hammer and drift (making sure the recess area is facing downwards) and then drill to pilot holes either side and countersink them (find out how to countersink screw heads in our project here).
Using 8 by 3-inch screws, screw a screw into each other holes to secure the cross piece timber to the mounting timbers.
Now, use a tape measure to mark the very centre of this piece of timber. Use the same flat wood bit or auger bit you used before to drill the dowel hole in the base and drill another hole of the same size.
Test Fit the Car Seat
With our seat mounting base now complete it is time to do a test fit to make sure seat mounting brackets fits snugly on the base and also that the seat itself sits level.
Place the mounting base down on a flat level surface and then place the seat on top of it. Maneuver it around until all four mounting brackets on the seat are sat equally on the mounting bracket.
Once in place use a spirit level to check the level of the seat.
As we were effectively making this project up as we were going along at this point we noticed a slight miscalculation in that the seat was tipping forward slightly and wasn’t sitting level so some further adjustments are needed.
Using a spirit level, lay one end of the level on the front of the seat and then lift the level up until it the bubble is dead level then use a tape measure measured from the base of the level to the front edge of the seat.
In our case here it’s 30mm so we no need to drop back of the seat down 30 mm.
On the back edge of the seat mount measure and mark down 30mm and then using an angle bevel set the angle to the slope of the mount, drop the angle down to the mark you just made and then draw a line down the blade of the bevel.
Next, measure the length of the rear mounting bracket on the seat and then transfer this measurement on to the line you just created on the mounting bracket then draw a vertical line up to the sloping face.
Using a hand saw, chop away this piece of timber and then repeat the same process for the other mounting bracket.
Give everything a sand down again and then pop your seats back on the mount to check that it is now level.
Work out How High our Office Seat Needs to be
One of the most important points about this project is making sure that your seat is at the correct height. Too high and your legs will be left dangling in mid air the knees knocking on the bottom of the desk or too short and you’ll be struggling to reach the top of your desk.
The height that your office chair needs to be set at very much depend on how tall you are.
The best way to figure out how high your chair needs to be is to sit on your existing chair and set it to the correct height then use a tape measure to measure from the floor up to the top of the seat.
When testing our seat it was 475mm from floor level to the top of the seat so this is how high our seat needs to be from floor level to top of seat level.
The main reason we need to figure this out now it’s because we need to know how all how to cut our centre support post to.
So with this in mind we need to total up he heights of all the different components we’re using, these are as follows:
- Height of casters = 50mm
- Base timber thickness = 42mm
- Base of mounting bracket to top of car seat = 200mm
Totaling up all of the above this gives us 292mm, meaning that our centre post needs to be cut at 183mm to give us our total seat height of 475mm.
Cut Centre Support Post to Correct Height
One of the final jobs to do now just cut our centre support post to the correct height so that it can be fixed to the base and then the mounting bracket can be fixed on top and then the seat fixed to the mounting bracket.
We’re going to need a sturdy piece of timber. In this case we are going to use a 100 x 100mm timber fence post.
Firstly, cut a section from the base of the fence post to ensure it’s totally square then measure and mark a point 183mm along the post and cut the centre support to this length.
Once cut, use your orbital sander or sandpaper in a sanding block fully sand the support post down taking off any rough edges.
Once sanded, stand the support post upright then mark across the top edge to define the centre point. Do the same at the other end also.
Using your flat drill bit or auger bit, drill a hole to a depth of 45mm at both ends so that post will easily slot over the dowel in the base and also so that we can add another dowel at the top.
Take the centre support and slide it over the dowel in the base to test the fit. Make sure that the centre support sits flat and square on top of the base.
Once tested remove it and spread wood glue inside the hole in the centre support and also some around the dowel and pop it back on and square it up.
Now, flip the entire base over and drill four pilot holes and countersink them and then insert 8 by 3-inch screws through the bass into the support to fully hold it in place.
Fix the Mounting Bracket to the Base
With the base now fully prepared it’s time to fix the seat mounting bracket in place.
Firstly, insert your other dowel into the top of the centre support post (add wood glue before you do) then add some wood glue to the hole in the mounting bracket and push it over the dowel.
As we did with the base, drill four pilot holes and then insert four 3 inch wood screws into each hole to clamp the mounting bracket down onto the base.
Fix Caster Wheels to the Bottom of the Base
Before we go ahead and fix the car seat down to the mounting base we need to fix the caster wheels to the bottom.
Flip the entire structure over and screw a caster wheel at each of the four corners.
As we will be using our new office chair on a solid hardwood floor we opted for small caster wheels but if you are to be using your chair on a softer surface such as a carpet then it’s advisable to use some bigger wheels as smaller wheels will just get jammed up with the carpet pile.
Add Support Brackets From Base to Centre Support
Regardless of how firmly the centre support is screwed to the base and the fact that we have also used a dowel, the constant movement applied by someone using the chair will eventually loosen the centre support from the base and the mounting bracket so we are going to need to add some bracing.
For this we are going to make some timber angle brackets and then bolt them to the centre support and to the base. This will then bolster the rigidity of the centre support and prevent any movement.
Using some offcuts of the 6×2 timber we used earlier, cut 4 100 x 100mm blocks and then mark a diagonal line through the middle of all of them and then cut through etc line to leave you with 4 triangular chocks.
Using an orbital sander or sandpaper, sand them off full and remove any sharp rough edges.
Next measure and mark 35mm up from the base of each bracket at the centre and then 30mm down from the top on two of the brackets and 50mm down on the other two. This so the bolts can pass through and not hit each other.
Now, using your 16mm flat bit, cut out two recesses in the sloping face, one horizontal and one vertical and then use your 8mm wood drill bit to drill a hole through each. Repeat this for the other 3 pieces of timber, but for two of them drop the horizontal holes down 15mm.
Now take one of the chocks and position it between the base and centre support and use a pencil to mark the hole in the base and support. Repeat this for the remaining 3 chocks and then use the 8mm drill to drill out all the holes.
Next use four 60mm M8 coach bolts for the base and then two 160mm coach bolts for the support, push them all into place add a washer and then screw on a nut and tighten them all using a 13mm spanner.
Fix Car Seat to Office Chair Base
With our base fully now prepared it’s time to fix our car seats to it.
Place the base in an upright position on a flat level surface and then take your car seat and place it on top of the mounting brackets.
Adjust it until the mounting brackets on the base of the seat are spaced equally on the seat mounting bracket and then use a sturdy pen such as a Sharpie and mark through the fixing holes in the mounting brackets on the base of the seat onto the mounting bracket for the chair framework and then lift the car seat off.
Using an 8mm wood drill bit, drill straight down through each of the marking points on the mounting base. Run the drill bit through several times to clear the hole fully and ensure the bolts don’t bind.
With your holes drilled now put the car seat back on top of the mounts, and using two M8 160mm coach bolts at the back and two M8 60mm coach bolts at the front push them up through the base of the mounting brackets and through the mounting brackets on the base of the seat.
Pop a washer over the top of each bolt and then screw on an M8 nut and tighten them fully using a 13 mm spanner.
With our car seat fixed firmly to our office chair base we have now completed construction of our office chair.
Making an office chair out of an old car seat it’s a fairly interesting project and on the whole pretty worthwhile as we now have very comfortable office chair for very little cost.