How to Build a Loft Bed for Adults

Construct sturdy frame; add mattress support.
How to Build a Loft Bed for Adults
Tom Greenspan
December 21, 2022

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If you have limited space in your bedroom, there are very few options to make your room bigger other than having major construction works to extend your home. So, how can you free some floor space in your bedroom? The simple answer is to build a loft bed, the bed is off the floor, and you have all of that space to take advantage of.

You may think that building a loft bed is a difficult process, but in this article, we walk you through the “how to” process step by step. We will focus on a queen-size loft bed for your comfort.

Let's get into it and learn how it's done and more such as:

  • The best way to install steps
  • Use multiple fixings for a secure loft bed
  • Add the finish of your choice.
  • FAQs answered.

Should you use nails or screws?

It's an age-old question that needs to be answered. When it comes to secure fixings, screws win every time. The tread on a screw enables the fixing to be tight and secure, whereas nails provide a solid fix. They can work free and develop the tell-tale signs of creaking.

However, screws have very little sheer strength and will break easily when placed on a shear load. Nails have excellent sheer strength.

 For this project, we will use several different screw sizes and  Kreg jig for accurate hole sizing and angles, together with coach bolts that will make the loft bed secure and tight.

What will you need?

Below is an inclusive list of everything that you will need to start this project:


  • Tape Measure
  • Saw - Jig Saw, Circular, Tables, or Milter Saw
  • Drill
  • Square
  • Sander
  • Kreg Jig 
  • Nail Gun


  • 4 - 4x4 at 6” Fence Posts - UNTREATED
  • 2 - 2x6 at 8”
  • 2 - 2x6 at 6”
  • 14 - 2x4 at 8”
  • 15 - 1x4 at 6” - if 8” boards are cheaper, buy those - you will have leftover scrap


  • Qty8 - 5/16” Carriage Bolts at 7” length
  • Qty8 - 5/16” Washers
  • Qty8 - 5/16” Cap Nuts (rounded top)
  • 3” Wood Screws
  • 2” Wood Screws
  • 2-½” Pocket Screws
  • 1-1/4” Pocket Screws
  • Countersink Drill Bit
  • Pocket Hole Plugs - Paint Grade, Pine, Oak - optional
  • Clamps
  • Safety Gear
  • Wood Filler
  • Sanding Supplies
  • Paste Wax
  • Finishing Supplies
  • Anti-Tip Kit

Cut List

  • 4 - 4x4 at 59” - Legs
  • 2 - 2x6 at 81” - Side Rails
  • 2 - 2x 6 at 70” - Head / Foot Rails
  • 2 - 2x4 at 81”  - Cleats
  • 4 - 2x4 at 81” - Upper Side Rails and Center Support Joists
  • 4 - 2x4 at 70” - Upper Head / Foot Rails
  • 1 - 2x4 at 59” - Front Guard Rail Ladder Leg
  • 4 - 2x4 at 8 ¾ - Lower Front Guard Rail Ladder Supports
  • 1 - 2x4 at 18” - Upper Front Guard Rail Ladder Supports
  • 2 - 2x4 at 55” - Guard Rail Side Upper Rails
  • 4 - 2x4 at 27” - Ladder Rungs
  • 15 - 1x4 at 67” - Slats

The estimated cost of this project is $200-$250

The dimensions of this queen-size loft bed are:

That's a width of 77 inches x length of 84 inches x  height of 59 inches.

Step 1

To start the project, let's follow a logical sequence in the construction process. Cut all four legs to size and two of the side rails, which are the mattress support. If you have a circular saw, this is the best tool for the job, but it can be done with a jig saw, or hand saw.

Notch a leg for the stairs as below, making sure the dimensions are correct, measure twice, and cut once!

Attach the side rails cleats with 2-inch screws, ensuring a space of 1 ½ inch as per the diagram.

Ensure you leave this 1 ½ inch on each upright to allow the header rail and the foot rail to be fixed securely. When attaching the header and foot rail you will need to have everything clamped together and square.

When you are satisfied with the dimension and angles, use a 7/16 inch drill through all 3 pieces (legs, rails, and cleat), making two holes on either side to accept the bolts that will make the loft bed secure.

Step 2

Its now time to attach the head rails and foot rails to the structure. Attach these rails to the side rails so they are level (flush) with the outside of the legs and the lower side rail, and use 3-inch screws to make the fixing secure and tight.

If you have a Kreg jig you can secure the 1 ½ inch timber to fix the supporting joists to the header and footer rail with 2x 1/2-inch pocket hole screws, then fix the upper side rails individually, But not the support for the ladder.

Step 3

Install your guard rail leg cuts, these will be 2 x 2 x 4-inch pieces. One will be long, and the other cut to the correct sizes as shown in the image above.

This will be the main structure for your ladder rungs, so ensure the remaining space will accommodate the 2x 4-inch timber snugly. You may need a mallet to knock the timber fully into place.

Attach the front upper side rails to the leg using 3-inch screws. After this attach the guard rail leg with 2-inch screws.

Step 4

Attach the upper headrails with 3-inch screws to create a secure fixing with the upper side rails.

Step 5

It's time to lay the slats that will support your mattress, it's recommended that the slats are laid approximately 2 inches apart.  Use 1 ¼-inch screws to make a secure fixing.

Step 6

You are now in the final stage of constructing your loft bed. Attach the remaining foot rails to the back and upper side rails.

To complete the fixing of the foot rails to the rear edge you can use pocket holes with your Kreg jig and make secure fixings with 3-inch screws.

Slide the Ladder Rungs into place and secure them with glue. You can choose to secure it with 3″ Wood Screws from the legs into the ends of the rungs, but this is optional and you can absolutely secure it with glue and call it a day!

Step 7

Before adding your mattress use filler for any unsightly wood finishes and add paint or stain as you wish before adding the mattress.


Are loft beds OK for adults?

It seems as if there is a misconception that loft beds are for kid's bedrooms only, but the truth is if the loft bed has a rigid contribution to take the weight of two adults in bed then it's perfectly fine for adults.

Loft beds are fun for adults. They provide a unique perspective on sleeping and may transport you back to your early years of sleeping on the top bunk.

If you use a memory foam mattress, you can add extra spacing in the slats if required to allow the mattress to breathe easily and keep you cool during your slumbers.

How much weight can a DIY loft bed hold?

Under normal circumstances, you could expect a loft bed to hold 200-250 lbs easily if it's designed for a twin mattress, which is the same as a twin bunk bed.

Loft beds can have a more robust structure and hold 600 lbs or more. If you are concerned about the weight capacity of the loft bed, you could always introduce center support for extra rigidity and peace of mind.

Store-bought loft beds are normally made of tube steel and powder coated. They are not strong enough for someone carrying extra pounds. More importantly, if you are carrying extra pounds, ensure the steps' rungs are robust enough to support your weight.

Is it OK to put a mattress on slats?

Bed slats can support any type of mattress available. It is advised to use a deep mattress. Remember that you do not have springs for support, so a decent mattress is a must for an adult loft bed.

Are loft beds worth it?

If you have a small bedroom and want to use it fully, then yes, a loft bed is worth it. Many young adults living with parents have a lot of clothes and computer equipment in a bedroom that makes it feel cluttered, closing the room in.

A loft bed is an ideal solution to free floor space and still be able to sleep comfortably. You can create a desk under the loft bed and a seating area that is comfortable and cool looking.

What's the disadvantage of a loft bed?

Making your bed, it's hard to throw your sheets on without climbing onto the bed. It's awkward and takes more time than normal.

During the warmer months sleeping closer to the ceiling can make sleeping uncomfortable hot if the ceiling is low. We all know heat rises and how being hot can prevent you from sleeping.