How to Measure Your Home and Build a DIY Crawlspace Draft
You don't need a laser scanner or a professional surveyor to get a useful, working diagram of your crawlspace. With the right approach — and the right tools on your phone — most homeowners can build a solid DIY Draft Blueprint in a single afternoon.
This guide walks you through the process: what to measure, how to measure it, and how to use those measurements in Crawl-Space Connect's DIY Draft Blueprint tool.
What You're Actually Mapping
A crawlspace blueprint captures the footprint and key features of the space under your home. For most homes on a standard crawlspace foundation, the crawlspace perimeter follows the building footprint closely. You're not measuring the crawlspace itself from inside — you're measuring the outside of the house to establish the outer wall layout.
From there, you layer in what you know is inside: vents, access doors, AC units, electrical boxes, and support piers.
The result is a map that anyone — a contractor, an inspector, a future buyer — can understand at a glance.
Two Ways to Start: Quick Entry vs. Walk-Around Wizard
Crawl-Space Connect gives you two paths for building your draft:
Quick Entry is for homeowners who already have a rough sense of their home's dimensions. If you know your house is approximately 40 feet wide and 60 feet deep, you can type those numbers in directly and get a basic rectangular outline on screen immediately. This works well for simple rectangular homes where you're more focused on documenting features than achieving precise wall-by-wall accuracy.
Walk-Around Wizard is for homeowners who want a more accurate outline, or who have an L-shaped, T-shaped, or otherwise non-rectangular building footprint. The wizard walks you around the outside of your home one wall segment at a time, prompting you to measure each segment and enter the length. When you complete the loop, the tool assembles your outline automatically.
The Walk-Around Wizard is designed to work with the iPhone Measure app — Apple's built-in augmented reality measurement tool — which lets you point your phone at a surface and get a reasonably accurate dimension without a tape measure. More on that below.
How to Use the iPhone Measure App for Wall Measurements
The iPhone Measure app uses your phone's camera and LiDAR sensor (on iPhone Pro models) or ARKit (on standard iPhones) to estimate distances. It's not as precise as a laser distance meter or a steel tape, but for the purposes of a DIY crawlspace draft, it gets you close enough.
Here's a practical approach:
Stand at a corner of your house. The best measurements come from a consistent angle — aim to stand at approximately 90 degrees to the wall you're measuring, with good lighting.
Open Measure, select "Ruler" mode. Tap to set your start point at one corner of the wall (at ground level, or at a consistent height). Walk to the opposite corner, keeping the phone aimed at the wall, and tap to set your end point. The app displays the measurement.
Take two readings per wall and average them. Measure readings can vary by a few inches depending on angle and lighting. Two readings give you more confidence.
Round to the nearest half-foot for entry. A DIY draft doesn't need to be to the inch. Rounding to 6-inch increments keeps entry simple and the map readable.
Note your starting corner. The Walk-Around Wizard asks you to walk in a consistent direction (clockwise or counterclockwise) so it can assemble the outline correctly. Decide before you start and stay consistent.
If you don't have an iPhone, a laser distance meter (available at most hardware stores) works even better — point at a wall from a few feet away and get an instant, accurate reading. A traditional tape measure works fine too, especially for shorter walls.
Handling Non-Rectangular Footprints
Many Charleston-area homes — particularly older bungalows, raised cottages, and homes with additions — have footprints that aren't simple rectangles. Garages, screened porches, bump-outs, and attached additions all change the shape.
A few practical tips:
Break it into rectangles. Most irregular footprints can be understood as two or more rectangles combined or subtracted. A main rectangle with an L-shaped addition, for instance, can be entered as the main body plus an attached wing.
Only map what sits over the crawlspace. A slab-on-grade garage attached to a crawlspace home doesn't have a crawlspace under it. You only need to map the portion of the foundation that sits over the actual crawlspace.
Annotate what you can't capture perfectly. If part of your footprint is genuinely irregular — a curved wall, a bay window, a diagonal section — sketch your best approximation and add a note in the description field. A close draft is still far more useful than no map at all.
Adding Features to Your Map
Once your perimeter outline is in, the real documentation work begins. Here's a checklist of what to add:
Access doors — Every entry point into the crawlspace. Note which side of the foundation they're on. If there are multiple, mark each one. This is probably the single most useful thing on the map for anyone doing work or an inspection.
Foundation vents — Mark each vent opening along the perimeter. If you know they're distributed evenly, you can place them at regular intervals. If some are blocked or have been sealed, note that in the description.
AC / HVAC equipment — Air handlers, evaporator coils, and ductwork that runs through or is located in the crawlspace.
Dehumidifiers — Increasingly common in Charleston-area crawlspaces, especially in encapsulated or partially conditioned spaces.
Electrical panels and junction boxes — Any electrical equipment located in the crawlspace is worth marking for safety and service reference.
Support piers and posts — If your crawlspace has visible structural supports, add them. This is most relevant for older homes.
Using "Find My House" to Skip the Blank Slate
Before you start measuring, check whether Crawl-Space Connect's Find My House feature can do the first step for you. Type your street address, and the tool pulls county building-footprint data to pre-fill your exterior wall dimensions automatically.
For many standard homes in Charleston, Berkeley, and Dorchester counties, this data is detailed enough to give you a near-ready outline to work from. You may only need to confirm or adjust dimensions, rather than measure from scratch.
If your home has had additions, renovations, or unusual geometry not captured in county records, you'll want to adjust the pre-filled outline — but you'll still have a better starting point than a blank grid.
What to Do After You've Built Your Draft
A DIY draft blueprint is a working document, not a finished one. After you've built the initial outline:
- Upload what you have. Any inspection reports, contractor quotes, or photos from past crawlspace visits belong in the document section of your blueprint.
- Share it with your next contractor. Before your next HVAC service call, encapsulation quote, or inspection, send them the blueprint link. It eliminates the "what do you have down there?" conversation.
- Plan a professional upgrade if needed. If your DIY draft reveals complexity you couldn't capture accurately — a finished basement area, a complicated mechanical layout, an addition with unclear foundation type — Crawl-Space Connect's professional 3D capture service ($499 one-time) delivers a field-verified, millimeter-accurate blueprint.
Ready to start your DIY Draft Blueprint? Head to [crawlspaceconnect.com](https://crawlspaceconnect.com) to create your account. The registry is $29/year, and the DIY Draft tools — including the Walk-Around Wizard and Find My House — are included.