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A homeowner preparing to install new flooring removed the baseboards and found gaps between the slab and foundation wall, along with loose, cracked concrete. The homeowner asked GreenBuildingAdvisor readers how to address the perimeter and where to seal around a bonus room and second-floor walls; the supplied report does not include answers or a confirmed repair.
A homeowner preparing to install new flooring has asked for advice on air-sealing gaps found with the baseboards removed in a 1993 slab-on-grade house. The question, posted to GreenBuildingAdvisor, describes loose and cracked concrete along the slab perimeter and asks where to seal around a bonus room and second-floor walls; the report supplied does not include a response or verified repair plan.
The homeowner says the house is in climate zone 4A and that all baseboards are off before new flooring is installed. At the main level, the homeowner found what they describe as large gaps between the slab and foundation wall. Concrete near the slab edge appears thin, cracked and loose, and seems to sit over foam insulation. These are the homeowner’s observations; the material and condition have not been independently confirmed.
The homeowner is considering removing loose concrete and using a self-leveling concrete sealant, naming a Sikaflex product as a possibility. The post asks how to handle the gaps and damaged-looking edge, but does not establish whether that product is suitable for the specific joint, whether the concrete should be removed, or whether there are underlying structural or moisture concerns.
The other questions concern a bonus room with knee-wall attics and the second floor. The homeowner says the subfloor appears continuous beneath a bottom plate and asks whether sealing should be done from the attic or the room, and whether to seal both the plate-to-subfloor and drywall-to-plate joints. The post also asks if the second-floor bottom plates should be sealed. No measurements, photographs, inspection findings or answers are included in the supplied material.
A Narrow Window Before New Flooring
With the baseboards already removed, the homeowner has temporary access to the wall-floor perimeter that will be harder to reach after new flooring is installed. The question matters because it concerns a practical decision about whether and how to use that access, while avoiding a repair that merely covers a visible gap without addressing the relevant air-leakage path.
It also illustrates a limit of advice based on a short description: cracked or loose concrete and foam at a slab edge can require an in-person assessment to distinguish an air-sealing detail from a concrete, moisture or construction issue. The post does not document energy losses, indoor comfort problems, water intrusion, or a safety hazard, so none can be inferred from the description alone.
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What the Homeowner Found
The house was built in 1993 and has slab-on-grade construction, according to the post. The homeowner says the baseboards were removed in preparation for new flooring, making the lower wall and plate area visible. They report searching for instructions aimed at homeowners and identify a Matt Risinger video as the closest resource they found, as well as articles by Martin Holladay about air-sealing bonus rooms.
The supplied report is a request for guidance, not a published diagnosis or project outcome. It records the homeowner’s questions and proposed approach, but provides no expert assessment of the slab edge, no confirmed description of the foam, and no information about local code requirements or the precise sealant specifications. Those limits matter when interpreting the suggested repair: a named product in a question is not an endorsement or a confirmed solution.
Repair Details Remain Unverified
The supplied source does not say whether GreenBuildingAdvisor readers or an expert answered the question. It also does not provide the exact gap dimensions, photographs, slab-edge condition beyond the homeowner’s description, or the sealant product’s technical details. It is therefore unclear what repair is appropriate and whether the loose concrete can be removed safely without affecting the slab edge or foam.
The air-sealing path in the bonus room is also unresolved. The homeowner describes a continuous subfloor and a bottom plate above it, but the source does not confirm how the knee-wall attic, floor assembly and drywall connect. Nor does it establish whether sealing only one joint, both joints, or a different location would address the leakage. No claim about energy savings, code compliance or successful results is supported by the report.
Inspect Before Sealing the Edge
The next useful step is to obtain an assessment of the actual slab perimeter and wall-floor assembly before removing concrete or applying sealant. A qualified building-envelope professional or contractor can inspect the loose edge, foam and joint dimensions, identify any moisture or structural concerns, and check that a proposed material is rated for the joint’s conditions and movement. The source does not report that such an inspection has occurred.
For the bonus room and upper floor, the homeowner would need to map the air barrier and confirm the connections among the subfloor, bottom plate, drywall and knee-wall attic. Any work should follow the product instructions and applicable local requirements; if the assessment finds structural damage or persistent water entry, the issue should be referred to an appropriate licensed professional rather than concealed with a bead of sealant. The original question’s eventual answer and any completed repair remain unknown.
Key Questions
What did the homeowner find after removing the baseboards?
The post describes gaps between the slab and foundation wall, plus thin, cracked and loose concrete near the slab edge. The homeowner says it appears to sit over foam, but that material was not independently identified.
Does the report confirm that Sikaflex sealant is the right fix?
No. The homeowner mentions considering a self-leveling Sikaflex concrete sealant, but the supplied report contains no expert recommendation or confirmed repair. Product suitability depends on the joint and its conditions.
Where should the bonus-room air sealing be done?
The source does not answer whether sealing should be done from the room or knee-wall attic, or which joints need treatment. It records questions about the bottom plate, subfloor and drywall connections, not a verified method.
Is there a confirmed energy or comfort problem?
No. The homeowner asks about air sealing, but the report supplies no measured air leakage, energy use, comfort symptoms or repair results. It does not establish the size or impact of any leak.
Source: greenbuildingadvisor.com
