TL;DR
Get backup power and energy gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
A homeowner with baseboards removed while preparing for new flooring reported gaps and loose concrete at the slab perimeter of a 1993 house in climate zone 4A. The homeowner also asked how to air-seal a bonus room with knee-wall attics and second-floor base plates; the supplied source does not include expert answers or confirm a repair plan.
A homeowner preparing to install new flooring has asked for guidance on air sealing exposed wall and floor edges after removing baseboards in a 1993 slab-on-grade house in climate zone 4A. The question describes gaps and loose concrete near the slab perimeter and asks where to seal around a bonus room with knee-wall attics and along second-floor base plates.
The homeowner said removing the baseboards offered a rare chance to inspect the bottom-plate area. On the main level, they found large gaps between the slab and foundation wall. At the slab edge, they described concrete as thin, cracked and loose, apparently above foam insulation. They proposed removing loose material and using a self-leveling concrete sealant, but presented that as an idea for advice—not as work already completed.
The question also concerns a bonus room beside knee-wall attics. The homeowner said the subfloor appears continuous beneath the bottom plate and asked whether sealing should be done from the room or attic side. They also asked whether a bead at the plate-to-subfloor joint would be enough, or whether the drywall-to-plate junction should be sealed too.
A third question is whether the same approach should be used along the second-floor bottom plates. The supplied GreenBuildingAdvisor material documents the homeowner’s observations and questions, but does not provide an expert response, inspection findings, or a confirmed repair method. The source cites a Matt Risinger video and articles by Martin Holladay as material the homeowner had consulted.
Air Sealing Before New Flooring
The timing matters because the baseboards are already off and the homeowner says this is the only planned opportunity to reach the lower wall junctions before new flooring is installed. Once the trim and flooring work are finished, some gaps may be harder to inspect or access. Identifying the right air-control boundary before closing the area can help avoid sealing a visible crack while leaving another connected path open.
But the reported condition is not just a routine trim gap: the homeowner describes cracked, loose concrete and foam beneath the slab edge. The source does not establish what the foam is, how the concrete is supported, or whether the gap is an air leak, a construction detail, or both. Those distinctions affect whether a flexible sealant is appropriate and whether loose material should be removed. A homeowner should not treat the proposed product or repair as validated by the question itself.
The bonus-room questions matter because a knee-wall attic can create several connections between indoor space and unconditioned areas. Sealing only one joint may not address other openings along the floor, wall, or ceiling boundary. The provided account does not include enough construction detail or an expert answer to identify the correct boundary for this particular house.
Products Worth Considering
Chemical Guys 16-Piece Arsenal Builder Car Wash Kit with Foam Cannon & Bucket
Autel MaxiScope MP608 4-Channel Automotive Oscilloscope
DEWALT 20V MAX XR 3-Speed Cordless Impact Driver Kit (DCF845P1)
As an affiliate, we earn on qualifying purchases.
What the Homeowner Found
The house was built in 1993, is described as being in climate zone 4A, and has slab-on-grade construction. The homeowner had removed all baseboards while preparing to install replacement flooring and wanted to use the access to inspect and seal the bottom-plate area.
In the original question, the homeowner said online guidance aimed at laypeople had been difficult to find. They referenced a Matt Risinger video and Martin Holladay articles about air sealing bonus rooms, while noting that their own configuration seemed different because the subfloor appeared continuous and the bottom plate rested on it. No independent assessment of that interpretation is included in the source material.
“I’ve currently got all of the baseboards removed in preparation to install new flooring.”
— The homeowner, in the GreenBuildingAdvisor question
Repair Details Still Unknown
The supplied source does not show an expert reply, a follow-up inspection, or evidence that any sealing work was done. It is therefore not established whether the slab-edge gaps should be filled, whether the loose concrete can safely be removed, or whether the proposed self-leveling sealant suits the location and materials.
The description also leaves open the exact construction of the bonus-room floor and knee-wall boundary, the size and continuity of the gaps, and whether air leakage has been measured. No information is provided about moisture, drainage, structural condition, applicable local requirements, or the condition of the foam. The homeowner’s description of the subfloor as continuous is an observation, not an independent confirmation of the assembly.
Confirm the Assembly Before Sealing
The next useful step would be to establish what the exposed slab edge and wall-floor junction are made of and how the bonus-room floor connects to the knee-wall attic. Because the source contains questions rather than a repair outcome, the appropriate seal location and material remain to be determined. If the concrete is unstable or the condition suggests a structural or moisture problem, the homeowner should seek an assessment from a qualified building professional before removing material or applying sealant.
For the bonus room and second floor, the homeowner would need guidance specific to the actual air-control boundary and the accessible joints before reinstalling trim and flooring. The provided material does not say whether an expert response or further work is planned, so no later milestone is confirmed.
Key Questions
What did the homeowner find after removing the baseboards?
The homeowner reported large gaps between the slab and foundation wall, plus thin, cracked and loose concrete at the slab perimeter above what they thought was foam.
Did the source confirm that self-leveling sealant is the right repair?
No. The homeowner proposed using a self-leveling concrete sealant after removing loose material, but the source provides no expert recommendation or confirmation that this product or method is suitable.
Where should the bonus room be air-sealed?
The source records the homeowner’s question about sealing from the room or knee-wall attic, but does not provide enough construction detail or an expert answer to determine the correct location.
Is there a confirmed repair plan or outcome?
No. The material supplied is a request for advice. It does not report completed work, an inspection, measured leakage, or a confirmed repair plan.
Source: greenbuildingadvisor.com
