Tips for building my 1st built-in? Where to source MDF in the US?

[gearhound]

My house has an awkward alcove and I’m going to build it out in a similar fashion to the one in this photo. I’ve got experience building chairs, beds, tables, file cabinets, etc…but I’m yet to tackle a built-in. These alcove built-ins are pretty big in the UK so I’ve been watching a bunch of ‘fitter’s’ videos and I’ve got a decent grasp on the process.
I use a lot of 5x5 sheets of baltic birch ply and was planning on using that, but seems most opt for MDF for its better ability to take paint/ease of machining/etc… I’ve only used MDF to make templates for furniture so I’m clueless on using it in cabinet construction. I assume there’s different grades of MDF like there are with plywood? Is the difference in quality as big as it is with high end baltic birch vs big box ply?
Also, I’d love to hear any tips/things I should be aware of while building this out being my 1st time. I’ve been referencing this post:https://www.popularwoodworking.com/wp-content/uploads/Built-in-Basics.pdf for the technique to scribe/flush it with my wall and think I’m going to use a fitting strip that press fits into mortises.
Thanks for any help/suggestions.

Cheers!

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[Packard]

MDF takes paint beautifully, but not any machined (sawn) or sanded surfaces.  Water-based paints will "raise the grain" on cut edges.  Dressing the machined edges with SealCoat (shellac) or BIN (pigmented shellac) will address that. 

Note that not many fasteners work well with MDF.  Confirmats are my preferred fastener. 

Also note that MDF is heavy.  A 4' x 8' foot sheet of 3/4" MDF is just under 100 pounds.  A 4' x 8' sheet of plywood is about 70 pounds. 

MDF is cheaper.  I saw it recently for $59.00 at Lowes.  It was much more expensive a few months ago.  I just looked on line and Lowes has no inventory locally on MDF.  So I don't know the current price or if it is even available.

 

[afish]

MDF is easy to find and yes there is some different types most common are
1.ultra light just as the name suggests its lighter and less dense.  Good for big cabinet doors to cut down on weight
2. MR which is moisture "resistant" not proof
3. MDX there are a few different brands out there but this is exterior grade MDF but its expensive.

Regular MDF can be found at HD/Lowes for the rest you will need to search some plywood suppliers in your area #2&3 can be tricky to find but ultralight is pretty common.  The edges as Packerd points out are the difficult part of painting MDF.  It will most likely take several coats of whatever you use to seal the edges.  Its like a sponge and will just soak up the first few coats.  There is a paper faced iron on edgebanding you can use if you prefer.  Pro tip 2 part epoxy makes the best edge sealant.  One other thing to remember is MDF likes to sag over time so wide shelves will/should have continuous back support.  Or some other reinforcement added to prevent sagging.  Mdf doesnt make the best box material I would probably make the finished pieces from MDF but some type of ply product for the rest. perhaps a pre finshed birch or maple or cabinet liner depending on the look you want.   

 

[gearhound]

MDF takes paint beautifully, but not any machined (sawn) or sanded surfaces.  Water-based paints will "raise the grain" on cut edges.  Dressing the machined edges with SealCoat (shellac) or BIN (pigmented shellac) will address that. 

Note that not many fasteners work well with MDF.  Confirmats are my preferred fastener. 

Also note that MDF is heavy.  A 4' x 8' foot sheet of 3/4" MDF is just under 100 pounds.  A 4' x 8' sheet of plywood is about 70 pounds. 

MDF is cheaper.  I saw it recently for $59.00 at Lowes.  It was much more expensive a few months ago.  I just looked on line and Lowes has no inventory locally on MDF.  So I don't know the current price or if it is even available.

MDF is easy to find and yes there is some different types most common are
1.ultra light just as the name suggests its lighter and less dense.  Good for big cabinet doors to cut down on weight
2. MR which is moisture "resistant" not proof
3. MDX there are a few different brands out there but this is exterior grade MDF but its expensive.

Regular MDF can be found at HD/Lowes for the rest you will need to search some plywood suppliers in your area #2&3 can be tricky to find but ultralight is pretty common.  The edges as Packerd points out are the difficult part of painting MDF.  It will most likely take several coats of whatever you use to seal the edges.  Its like a sponge and will just soak up the first few coats.  There is a paper faced iron on edgebanding you can use if you prefer.  Pro tip 2 part epoxy makes the best edge sealant.  One other thing to remember is MDF likes to sag over time so wide shelves will/should have continuous back support.  Or some other reinforcement added to prevent sagging.  Mdf doesnt make the best box material I would probably make the finished pieces from MDF but some type of ply product for the rest. perhaps a pre finshed birch or maple or cabinet liner depending on the look you want.   

Thanks for the quick responses guys! Sounds like Home Depot/Lowe's grade MDF is fine to use then? I've used some of their plywood for garage projects and it's pretty bad (lots of voids, thin veneers, warped, etc), figure MDF is a lot easier to make but just wanted to confirm before buying a sheet.

I'm planning on using dominos for the joinery as I've seen that screws don't hold well in MDF. I've watched a guy named Peter Millard who's in London and builds out a lot of fitted alcoves with MDF....basically going to follow his process for assembly (https://www.youtube.com/watch?v=3utevJ8-p-k)

From a finishing/strength standpoint, I think it maybe easier to make the unseen internals of the cabinet with baltic birch ply and then just do the doors and fillers strips with the mdf? That way I'm only painting the fronts and can finish the inside with OSMO oil.

 

[Packard]

My process for dressing the edges of MDF is as follows:

Sand the edges with 150 grit sandpaper.  (I hand sand--I don't use a palm sander).
Rub in Parks Grain Filler and allow to dry.
Hand sand again.
Apply either SealCoat or BIN pigmented Shellac primer.
Then prime the entire project and then paint.

I get the Parks filler in the floor finishing department at Lowes or Home Depot.  It dries very fast and sands extremely easily.  The consistency allows me to apply it like shoe polish.  The sanding after filling will be minimal.

I have also laminated two thicknesses of MDF at the edges.  This treatment will make it appear as seamless. 

 

[afish]

miterfolding MDF works great too.  I miterfold anything I can but it can tricky depending on tools, equipment etc. 

 

[Crazyraceguy]

I would agree with what has been said above, but add that if your project is at all similar to the picture, don't make the shelves as a double layer of 3/4" material. I would do it out of 1/4" MDF and with a plywood inner structure (torsion box)
This has several advantages.
Less material overall
Far less weight
Easier install because of the weight and handling. You could put it on with a 3-sided cleat and just slide it in place, caulk, and paint.
The hollow core is easier for your wiring, if you go that route
It will be far stiffer, less sagging over time.
Plus, you can use the extra from the sheet to make your door panels.

Regular drywall spackle will also work well to seal the cut edges, but I still try to eliminate the ones I can. Take the upper shelf "sides" for example. Rather than simply nailing a filler onto the side and having to fill the edge of the side and the seam where it meets the filler, I would miter-fold that joint and never have to deal with it again.

 

[semenza]

MDO is another good choice.

Seth

 

[afish]

Rather than simply nailing a filler onto the side and having to fill the edge of the side and the seam where it meets the filler, I would miter-fold that joint and never have to deal with it again.

Exactly, and leave a little extra material on the leg that meets the wall so you can scribe it to the wall and ceiling this way the 2 vertical sides can be kept 100% parallel, square and co-planer so the shelves dont need to be custom fit on 3 sides. 

 

[Packard]

And never use MDF in wet areas.  Bathrooms would be a bad spot of MDF.  A coffee bar might also.  MDF absorbs water and swells. 

In the right situation, MDF can be an ideal product.  It takes paint beautifully, it is relatively inexpensive.  It does not chip when sawn. 

I have a 1/16 router bit for easing the edges.  It is more uniform than sanding.  Get the one that is solid carbide without the roller bearing.  It will get into tight corners.

MDF is the material of choice for speaker enclosures.  It does not resonate much and it is easy to work with.  (And there is little in the way of strength requirements in  speaker enclosures. 

 

[DynaGlide]

Not sure if I saw it mentioned but what you want is combi core. Mdf faced plywood core.

Kicking myself for not using it on my last painted project.

 

[gearhound]

Not sure if I saw it mentioned but what you want is combi core. Mdf faced plywood core.

Kicking myself for not using it on my last painted project.

MDO is another good choice.

Seth

Just called up one of my hardwood dealers (Sears Trostel in the Fort for those familiar) and MDO is $194/sheet; Baltic Birch is $217/sheet for 4x8 and $147/sheet for a 5x5; and MDF is $51. I luckily stocked up on sheet goods and rough sawn hardwoods a few years ago so I haven't had to buy anything during this craziness....but currently down to just one 5x5 of baltic, one maple and two walnut 4x8's with a mdf core. Anyways, the pricing has me leaning towards possibly just building the entire thing out of MDF. According to my hardwood dealer there's not really a difference in MDF quality sourced from them vs. the big box stores? He says there's only a couple places in the US that make MDF and it's all comparable quality.

 

[Packard]

A note:  My van easily transports 4 x 8 sheets of plywood.  But MDF is 97” x 49”.  The 49” dimension is really, really tight in my van and it scuffs up the wheel wells.  I will probably ask the lumber yard to rough cut it so it fits more easily in my car.

Lately I’ve been buying for the project and cutting to finished size on my driveway with the track saw.  I did not have that much faith in the track saw in the beginning, but I am confident that I can cut to finished sizes and it makes carrying plywood to the basement so much easier.

 

[Crazyraceguy]

According to my hardwood dealer there's not really a difference in MDF quality sourced from them vs. the big box stores? He says there's only a couple places in the US that make MDF and it's all comparable quality.

Depending upon what your dealer actually sells, there may be one difference. The typical stuff from the home center type stores is 4' x 8'. The stuff they sell at actual suppliers is sold as 49" x 97". This way you can still have a full sized sheet after you cut off the factory edges, being sure that it is square and undamaged. It also allows you to get 2 full 24" strips or 4 strips that are 12", which you can't from the 4' x 8' sheets.

 

[afish]

I will agree with MDF is pretty much MDF statement.  I have never noticed a notable difference in quality no matter where I got it. However, Im pretty sure the HD by me is selling 49x97 IM not 100% but 98% only because I havent bought any from there in a long time and things could have changed. 

 

[Packard]

Home Depot (and Lowes, and probably Menards) sell 49 x 97 because they are guilty of rough handling and the edges of the boards get damaged.  Then the customer complains that they are not really getting a 4 x 8 sheet because of the edge damage.

The oversized sheets eliminate that complaint. 

 

[Crazyraceguy]

I haven't bought any in a retail environment in quite some time, but around here, 4 x 8 (same as ply) is, or at least was, the norm, especially with 1/4" sheets. Until I started working in the cabinet shop in '04, I had never heard of 49" x 97"