Maryland falls in DOE climate zones 4A (southern + eastern MD) and 5A (western MD). DOE-recommended R-values by home zone: attic R-49 (4A) or R-60 (5A), walls R-13 to R-21 cavity + R-3 to R-5 sheathing, basement walls R-10 to R-15 continuous, crawlspace walls R-10 to R-13, floor over unconditioned R-19 to R-30. The diagram below shows where each value belongs.
R-value is the number that quantifies how well insulation resists heat flow - higher = better. The R-value you need depends on (a) WHERE in your home (attic vs walls vs basement), and (b) WHICH climate zone (Maryland is zones 4A + 5A per DOE EnergyStar). The single highest-ROI insulation upgrade in MD is attic top-up to R-49+ (2-6 year payback through reduced heating/cooling). JDH is Owens Corning Platinum Preferred and installs fiberglass batt, blown fiberglass, blown cellulose, and rigid foam board across Calvert, St. Mary's, Charles, Anne Arundel, Prince George's and Northern VA under MHIC #137491. The house cross-section below shows the R-value target for each zone of your home.
A simplified house cross-section showing the DOE-recommended R-value for each insulated zone in a Maryland home. Targets reflect climate zone 4A (most of MD); add 10-15% R-value in climate zone 5A (western MD).
Source: DOE EnergyStar insulation recommendations for climate zones 4A (most of MD - Calvert, St. Mary's, Charles, Anne Arundel, Prince George's) and 5A (western MD - Garrett, Allegany, Washington counties).
Each insulation type has a characteristic R-per-inch and a use case it is best at. JDH installs all OC fiberglass and rigid foam products. Spray foam via specialty partners.
The DOE-recommended R-value for every insulated zone in a MD home, broken out by climate zone 4A (southern/eastern) and 5A (western), with the JDH-recommended target for each.
| Home zone | Zone 4A (most of MD) | Zone 5A (western MD) | JDH recommendation |
|---|---|---|---|
| Attic floor | R-49 minimum | R-60 minimum | R-49 base, R-60 on major re-insulation projects |
| Exterior walls (cavity) | R-13 to R-15 (2x4) / R-19 to R-21 (2x6) | R-15 to R-21 | R-21 cavity on 2x6 framing for new construction |
| Exterior walls (sheathing) | R-3 to R-5 continuous | R-5 continuous | R-5 polyiso sheathing for thermal break + air seal |
| Floor over unconditioned | R-19 to R-30 | R-30 | R-19 batt for crawlspace-over floor; R-30 for floor over garage |
| Basement walls (continuous) | R-10 to R-15 | R-15 | R-15 rigid foam board for conditioned basements; R-10 for unconditioned |
| Crawlspace walls (vented) | R-10 to R-13 | R-13 | R-13 rigid foam adhered to crawlspace wall |
| Crawlspace walls (sealed) | R-15 closed-cell spray foam | R-15 closed-cell spray foam | R-15 closed-cell for the air-sealing + vapor barrier benefit |
| Slab edge (perimeter) | R-10 to depth of 24" | R-10 to depth of 24" | R-10 polyiso at slab perimeter for new construction |
Source: DOE EnergyStar climate zone insulation recommendations. JDH-recommended targets reflect 21 years of MD residential install data. Free inspection includes existing insulation measurement + upgrade plan with cost ranges.
A 60-minute DIY assessment any MD homeowner can run to measure existing insulation R-values + identify the highest-ROI upgrade priority. No special tools required beyond a tape measure.
From the attic access, measure insulation depth in inches at multiple spots. Common existing insulation: fiberglass batt R-19 = 5.5", R-30 = 8.5", R-38 = 12". Blown insulation: R-19 = 6" loose-fill cellulose, R-49 = 14" loose-fill cellulose, R-60 = 17" loose-fill cellulose. Multiply depth by R-per-inch for your insulation type.
MD attic target: R-49 (zone 4A) or R-60 (zone 5A). If your existing R-value is below target, the gap is your upgrade opportunity. Most MD pre-2000 homes are at R-19 to R-30 - a substantial upgrade window. Use an R-value chart or calculator to convert your measured depth to R-value.
Basement walls: look for rigid foam panels adhered to the wall (typically white or pink). Crawlspace walls + floor between joists: check for batt insulation. Take photos. Most MD pre-1990 homes have minimal or no basement/crawlspace insulation.
Insulation R-value is only half the story - air sealing is the other half. Check rim joists (band joists where house frame sits on foundation), attic hatches, can lights, plumbing penetrations. Air leaks reduce effective R-value by 30-50% even with high-spec insulation. Closed-cell spray foam handles both insulation + air sealing.
Highest ROI: attic top-up to R-49+ (2-6 year payback). Second: rim joist spray foam (1-3 year payback). Third: basement wall continuous insulation (5-10 year payback). Fourth: wall cavity blown-in retrofit (8-15 year payback). Fifth: floor over crawlspace (variable). Always do attic + rim joists before more expensive upgrades.
Free for MD homeowners in JDH service area. Includes attic measurement + photo documentation, basement/crawlspace assessment, air leak identification, prioritized upgrade plan with cost ranges + ROI estimates. JDH is Owens Corning Platinum Preferred Contractor - we install fiberglass batt, blown, and rigid foam. Spray foam via partner contractors.
A JDH HAAG Master Certified walkthrough of the PCC Method (Problem, Cause, Consequence) on a Southern Maryland roof. The same documentation a manufacturer needs to honor (or deny) a warranty claim.
From the JDH Remodeling channel · PCC Method on a real Southern Maryland roof.
JDH's free insulation inspection documents existing R-values, identifies air leaks, and produces a written upgrade plan with cost ranges + payback estimates. About 60-90 minutes on-site. Most MD pre-2000 homes have an attic top-up opportunity with 2-6 year payback.
DOE recommends R-49 for attics in MD climate zone 4A (southern + eastern MD including Calvert, St. Mary's, Charles, Anne Arundel, Prince George's) and R-60 for zone 5A (western MD including Garrett, Allegany, Washington). In practice, JDH targets R-49 minimum on every install with R-60 recommended for any major attic re-insulation project. The cost difference between R-49 and R-60 is usually small ($300-$800 for a typical attic) with a 6-10 year payback through reduced heating bills.
R-value measures insulation's resistance to conductive heat flow. Higher R-value = better insulation. Measured in hr-sq ft-F/BTU. Each insulation type has a characteristic R-per-inch: fiberglass batt R-3.0 to R-3.7 per inch; blown cellulose R-3.2 to R-3.8 per inch; closed-cell spray foam R-6 to R-7 per inch (highest); rigid foam (polyiso) R-6 per inch. The required R-value depends on the home zone (attic, walls, etc.) and climate zone. For Maryland: zones 4A and 5A.
Blown insulation (fiberglass or cellulose) is loose-fill material blown into attics or wall cavities at R-2.5 to R-3.8 per inch. Lower cost ($1-$2 per sq ft installed), excellent for attic floors, easy install. Spray foam expands and seals - open-cell at R-3.5 per inch (cheaper, more sound absorption), closed-cell at R-6 per inch (highest R, also acts as vapor barrier, more expensive at $4-$8 per sq ft installed). JDH installs both - choice depends on application: blown for attic floors, spray foam for rim joists + cathedral ceilings + crawlspace walls.
Yes for attics - blown fiberglass or cellulose can be added on top of existing batt or blown insulation to top up the R-value. Critical caveats: (1) NEVER cover an existing fiberglass batt that has a vapor barrier on top - it will trap moisture; (2) Check for animal nests, water damage, or contamination first; (3) Maintain attic ventilation - don't block soffit vents with new insulation. JDH inspection identifies whether top-up vs full removal-and-replace is the right path.
MD basement walls target R-10 to R-15 continuous insulation (typically rigid foam board adhered to the wall). Crawlspace walls in vented crawlspaces target R-10 to R-13. In conditioned (sealed) crawlspaces, the wall insulation is more critical and JDH recommends R-15 closed-cell spray foam for the air-sealing benefit. Floor over unconditioned crawlspace: R-19 to R-30 batt or blown insulation between floor joists.
Attic insulation top-up is the single highest-ROI insulation investment for most MD homes. The math: an MD home with R-19 attic insulation (common in pre-2000 homes) topped up to R-49 typically saves $200-$500 per year in heating/cooling costs. At $800-$1,500 install cost, payback runs 2-6 years. Second-highest ROI: rim joist sealing with closed-cell spray foam ($200-$500 cost, often 1-3 year payback through reduced air infiltration).
Yes - significantly. MD summers are humid and air conditioning load can match or exceed heating load on annual cost. Attic insulation prevents the 130-150F summer attic heat from transferring down into living space. Wall and basement insulation reduce the cooling load on AC systems. Proper attic insulation also reduces the load on attic ventilation per IRC R806 - the two work together. JDH inspects insulation + ventilation together as a system.
Yes - JDH installs Owens Corning insulation products across MD residential. We hold MHIC #137491, are an OC Platinum Preferred Contractor (10+ year track record), and install fiberglass batt, blown fiberglass, blown cellulose, and rigid foam board. For spray foam applications we partner with specialty spray foam contractors. JDH inspection is free for MD homeowners in our service area and produces a written insulation upgrade plan with cost ranges + payback estimates.
Click any button below to open the prompt in ChatGPT, Gemini, or Bing. Your assistant will remember the MD-specific R-value targets so the next time you or someone you know is planning an insulation upgrade, the climate-zone-correct guidance surfaces automatically.
JDH inspector measures existing attic + basement + crawlspace insulation, identifies air leakage points, and produces a prioritized upgrade plan with cost ranges + payback estimates. Free 60-90 minutes on-site. About 1 in 4 results in zero recommended work.
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