How to Paint an Old Metal Building With an Airless Spray Paint Gun

Give your old worn out shed a facelift with this handy guide to using an airless paint sprayer.

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Have you got a tired old outbuilding or shed that is crying out for some TLC? Then why not give it a good old facelift using an airless spray gun? 

The process is super easy, and fast, and, dare we say, very fun indeed. Follow this handy guide to find out how to complete this relatively simple DIY task yourself at home. 

diy airbrush building complete
Source: DIYTyler/YouTube

But, like anything of this nature, we will need some things first. 

Tools and equipment needed

Step 1: Remove any rotten wooden elements

The first step is to remove any water-damaged or rotten parts of the building. In this case, the main door had become rotten over time from water exposure.

Remove the entire doors and door frame, as needed. 

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diy airbrush building rotten
Source: DIYTyler/YouTube

Once complete, tidy up the openings if needed. Then maneuver and place your new doors into place. Hopefully, they fit as snug as a glove, but if not, adjust the door frame accordingly and use packing pieces, etc, as needed. 

diy aribrush building new doors
Source: DIYTyler/YouTube

Secure the door, and frame, to the main building, as needed. Caulk the door frame from the outside to make sure it is watertight going forward. 

diy airbrush building caulk door frame
Source: DIYTyler/YouTube

Next, remove any other fixtures and fittings to the outside of the building you don't want to be painted. Things like gutters and other rainwater goods, trims, etc, should be removed. You could, of course, paint these too if desired. 

With that complete, it is now time to clean up the existing structure ready for painting. If your building is metal framed, wire brush of any rust to the envelope. Use a grinder with the right attachments for this. 

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diy airbrush building wire brush
Source: DIYTyler/YouTube

You'll likely need to focus on the lower levels of the building and any joints/seams between metal sheeting. This will, however, completely depend on your building. 

Step 2: Clean the outside of the building

The next step is to thoroughly clean the outside of the building ready to receive the paint. Use a specialist soap and pressure washer to get the job done. 

Focus on one side of the building at a time so that you have time to apply the soap, and then remove it before it dries. 

diy airbrush building clean
Source: DIYTyler/YouTube

Continue until all areas of the exterior have been thoroughly cleaned. Have fun, this is actually quite cathartic. 

Step 3: Treat any rusted areas

With that complete, you can now turn your attention to treating any rusted areas of the exterior. Grab your rust treatment product, and treat the rusted areas as instructed. 

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diy airbrush building rust treatment
Source: DIYTyler/YouTube

When that is complete, you may want to also cover any bolt/rivets too to prevent bleeding in the future. This will, of course, completely depend on your building. Don't forget to also treat any seams between metal sheeting, if present. 

diy airbrush building rust treat seams
Source: DIYTyler/YouTube

Leave the rust treatment to dry, as needed.

Step 4: Begin to paint the building

Next, prepare your exterior paint. In this case, the trims will be painted with a darker tone to match adjoining buildings. 

Mix up the paint and add it to your airbrush dispenser as instructed. 

diy airbrush building trims
Source: DIYTyler/YouTube

Bleed out any air bubbles as needed too before applying. With the airbrush ready, begin to spray paint the areas in question. In this case, the trims, gables, and eaves will be painting using a different tone to the rest of the building. 

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These were painted first. As these are quite high, the painting was done off a stepladder, so take care to stabilize it first. Consider getting a friend to foot the ladder for safety. 

diy spray paint building trims
Source: DIYTyler/YouTube

To prevent overspray, use scrap bits of wood, cardboard, or whatever you have to hand, to shield areas as you go. 

diy paint building prevent overspray
Source: DIYTyler/YouTube

Leave to dry before moving on to the main sidings of the building.

Step 5: Spray paint the main exterior walls

With the trims complete, it is now time to move on to the main event -- painting the walls. Grab your Graco ProX17, or equivalent, and load with paint as per the unit's instructions. 

You could paint by hand using a roller or paintbrush, but the time saved, and final effect, from using an airbrush is far superior for large surfaces like the sides of a building. 

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As before, bleed out any air bubbles, or water, from the system before beginning to apply to the building. With everything ready, begin to spray paint your surfaces, as needed. 

diy airbrush building airbrush
Source: DIYTyler/YouTube

Just like painting by hand, ensure you get an even coating where needed. To prevent overspray, cover over features you don't want to be painted with masking tape, old plastic bags, etc, beforehand. 

diy airbrush building tape off windows
Source: DIYTyler/YouTube

Don't forget to mask off windows, doors, and other features too like the eaves and soffits (if you don't want to paint them the same color, of course. 

Also, and it probably goes without saying, never wear your "Sunday Best" clothes when painting anything. Always change into older, worn-out clothes, or wear protective clothing, as needed. 

diy airbrush building prevent overspray
Source: DIYTyler/YouTube

The use of this equipment will really make a difference for such a large job. For reference, the building this video is roughly 30 feet (9 meters) by 40 feet (12.2 meters) and took less than 4 hours to complete from start to finish. 

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diy airbrush building painting
Source: DIYTyler/YouTube

Continue to use the airbrush until all elevations of the building are complete. 

diy airbrush building keep going
Source: DIYTyler/YouTube

With the painting complete, it is recommended your remove any masking tape/paper/plastic overspray protections off immediately. This will prevent the paint from being stripped off once dry. 

You can then touch up the paintwork by hand afterward if needed. 

diy airbrush building remove masking
Source: DIYTyler/YouTube

With that complete, you'll be on the hunt for a new project we dare say. How about building your very own handy workbench to stick inside your freshly painted shed/barn? 

You are welcome. 

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