Nobody builds exactly what is on the permit drawings. The window supplier substitutes, the owner wants a bigger patio door, the installer has a different furnace in stock. Normal life on a job site.
The trouble starts when the house no longer matches the paperwork and nobody tells the building department. Here is what needs a revision, what does not, and how to keep the final inspection from turning into a surprise.
More glass means more heat loss and can push you past your SB-12 package limits. See SB-12 explained.
A cheaper window with a higher U-value than the drawings show changes both the heat loss and the energy form.
A different furnace, heat pump, boiler or HRV than the drawings show. Size, type and efficiency all matter.
Going from forced air to radiant, or adding a heat pump. That is a redesign, not a footnote.
Moving walls, adding rooms or finishing space that was not finished on the drawings.
Less insulation than the drawings show, anywhere. That one almost always comes back.
If the HRV, fans or ventilation layout change, the ventilation summary (RMVDS) has to be updated too.
Adding insulation beyond the drawings, upgrading to better windows of the same size, or a same-size equipment model swap with equal or better efficiency usually does not cause trouble. Even then, tell your designer and keep the paperwork matching what you built.
If in doubt, ask the building department. They would much rather hear about a change before the inspection than find it during one.
Upgraded insulation or better windows lower your heat loss. A quick re-run may let you buy smaller equipment. That is the only revision that pays you back.
The moment a substitution comes up, ask what it does to the drawings.
The designer updates the heat loss, the equipment schedule and the energy values.
Revised drawings go to the building department for review before the work is done.
Then the inspector sees a house that matches the paper.
If we did your design, send us the change and we update it. If someone else did, we can work from their drawings and your changes. Either way the revised package is signed and ready to submit.
Got a deficiency notice already? See what to do when HVAC drawings come back.
Something changed on site? Send us what changed. We update the numbers and the drawings so the inspection goes through.
Get Free Quote →If the change is real, yes. Bigger windows, more windows, or windows with a worse U-value change the heat loss and can break your SB-12 package. Smaller or better windows usually help, but the paperwork should still match what you built.
It can be. If the new one is a different size, type or efficiency, the drawings and the energy form no longer match. Send a revised equipment schedule to the building department before it goes in, not after the inspector spots it.
Adding insulation beyond what the drawings show rarely causes trouble, but tell your designer. It lowers the heat loss, and you may be able to use smaller equipment. That is money back.
Usually the inspection fails until you submit revised drawings and get them reviewed. On a tight schedule that can hold up occupancy. Much easier to revise first.
It depends on what changed. A swap of one piece of equipment is a small job. A redesign of the layout is bigger. Either way it costs far less than failing the final inspection.
Revised design documents should be signed by the designer responsible for them, the same as the originals. That is part of what a revision is.
Send the approved drawings and what changed. We update the heat loss, equipment schedule and energy values, signed and ready to submit.