How to DIY Build an Exterior Crawl Space Door

Now that we’ve replaced the siding and installed the trim on the exterior walls of the Fixer Upper Main House here at One Hundred Acres Home, it’s time to wrap up the finishing touches. That includes building a new exterior crawl space access door. This post will show you an easy way to build a crawl space door that will give you smooth, lockable access while keeping critters out.

First, here is a photo of where we left off with the siding and the trim. I want to get the crawl space door installed before I give everything it’s final coat of paint.

Old Crawl Space Door:

Before we get to the new door, let me show you the old door and explain why it wasn’t working.

The old door is located to the on the right side, just left of the electric meter (covered by the tree trunk in the photo). There is an arrow pointing to the old access door to the photo below.

You should be able to click on the photo above for a larger view if you like. As you can see, the old door was basically a cut panel of plywood siding that is attached on top of the general siding.

You can see the crawl space panel is slightly crooked. It was not attached with hinges or anything solid, but rather, some old wood screws at the top corners, screwed into the main siding. Each time you wanted to access the foundation, you needed to unscrew and then re-screw those same holes. They were wearing out over time.

Also, the door would not attached snugly to the siding so mice and rats were finding their way into the crawl space and making nests in the floor insulation. YIKES! Overall, it was a disappointing set up. Let change that.

New Exterior Crawl Space Door Requirements:

The main requirements of this new exterior crawl space door are:

1. It needs to look good! And fit in with the rest of the board and batten siding look.
2. It needs to be mounted with door hinges so it swings open and closed easily.
3. It needs a lock option to lock the door from the outside.

Door Frame:

We’ll be using the same framing opening as the old door for the new one. The opening will be approximately 24 inches wide x 24 inches tall. That is slightly larger than our local code requirements for a minimum crawl space access opening of 24 inch wide x 18 inches tall.

Here is a photo of the exposed framing during the siding demolition. You can see the framing opening for the crawl space door is the large cap between wall studs.

Door Flashing:

I kept the flashing really simple here. At the tops and sides, I simply wrapped the Tyvek house wrap into the frame and stapled it to the wood with the typical Stringer capped staples. Here is the upper corner of the door frame where you can see the house wrap and staples.

For flashing at the bottom of the door, I covered with the same Dupont Tyvek FlexWrap, a flexible door sill flashing tape used at the exterior doors. This is an flexible asphalt-based tape with a tough fabric-like cover. Here is a close up of the Flex Tape.

You can see the tape is quite wide. It’s wide enough that about half of that width will cover the top of the door sill while the other half extends down over the house wrap.

Here is a clear picture of the FlexWrap at the door sill that continues down over the house wrap. I installed it exactly this way at the base of the crawl space door.

This is the full crawl space opening where you can see the flex wrap at the bottom sill. It is a bit dirty as I use the crawl space for material storage so I am constantly crawling in and out of here. But the good news is that this tape is tough and wear-resistant.

Crawl Space Door Panel:

This is an easy build! Since we used smooth T1-11 plywood panel siding for the typical exterior siding of the Main House, we’ll use the same material for the crawl space door panel.

I want the door fit snugly enough in the frame that small rodents cant get in. However, I also want the door to swing relatively freely. Remember our opening dimensions are 24 inch x 24 inch. I decided to cut the door panel just a hair smaller at 23 5/8 inch x 23 5/8 inch. I will center the door in the opening to install it, so that will leave just a hair under 1/4 inch gap around all sides. Small ants can get through here, but small ants can also get through the crawlspace vents. As long as we keep the mice and anything larger out, I’ll be happy.

So, I cut the main panel for the door our of the smooth T1-11 plywood. Here a close-up of the smooth T1-11. You can see it still has a wood grain.

Next, I cut an opening in the center of the door for a crawl space vent. It’s easiest to cut a hole in the center of a plywood panel if you start it with a hole drill. Here’s my work station with the hole drill set up.

Once the four corner holes are drilled, you can use a jig saw to cut out the rest of the opening.

With the basic door panel cut, I primed all sides to give it extra weather protection. Here is the back side of the crawl space door where you can see the cut opening for the vent and the primed edges.

Finishing Touches:

To match the door to the rest of the house, I used the same 1×3 radiata pine trim as we used to achieve the exterior board and batten look. I framed out the opening with the trim and also installed the trim around the perimeter of the door panel. Then, I hung the door directly to the framing trim with two exterior door hinges as you can see in the photo below.

You can see all the trim nail heads now, but those will get painted over to clean up the look. I also added a slide-bolt door latch as you can see in the photo above. It has a small loop that allows for a padlock option if you want. It’s hardly noticeable, but can you see that I added a small piece of trim behind the door latch? That was needed so the latch would sit evenly.

For the door vent, I used small screws into the door panel, but they we still long enough to break through the back of the plywood. To avoid getting snagged by the pointy end, I cut those off with some small end cutting pliers. If I really want a smooth finish, I sand down the cut end of the screw with a flat metal file. Then paint over everything and no one will realize you used a screw that was too long.

Finally, the built exterior crawl space door was painted along with the rest of the exterior. Here is the final result.

Doesn’t this look WAAAAY better than the old panel? I am happy to report that mice and rats no longer have free range access to the crawl space. Soon I’ll be replacing the under floor insulation where they made their nests (UGH!). Wish me luck.

I’d love to know if this helped you with build an exterior crawl space door. Let me know in the comments below.