Home Depot Lost $49 Million in Fiberglass — and Found Growth in Board
Home Depot's insulation business totaled $1.02 billion, down 5.0%. Fiberglass batts account for $613 million but dropped $49 million. Distribution held flat — the problem is velocity. Units per store fell 12% while price rose 6%. Shoppers bought fewer batts at higher prices.
Owens Corning leads at $576 million and roughly 57% share, but it is shifting its Home Depot mix from fiberglass batts (−$34 million) toward foam board (+$6 million), where it now holds 56% of the segment.
CertainTeed grew from $9.5 million to $24.9 million (+162%), building a Southern fiberglass business from near zero with 56% more stocking stores. Johns Manville fell 25% to $85 million, with $20.9 million of that loss in the South. CertainTeed is filling the gap Johns Manville is creating.
Lowe's Bet on Mineral Wool — and It Is Paying Off
Lowe's generated $668 million, down 4.2%. Batts dropped $35 million, mirroring Home Depot. But Lowe's has a growth story Home Depot does not: mineral wool, up $9.7 million or 14%, driven almost entirely by ROCKWOOL.
ROCKWOOL reached $78 million at Lowe's (+21%), adding stocking stores at a 20% rate. In the Northeast, ROCKWOOL accounted for 94% of the region's $4.9 million in insulation gains. The shelf economics support the shift — mineral wool batts return $33 per unit on hand, ahead of fiberglass at $28.
The Regional Picture Follows Housing Starts
The Northeast was the only region to grow (+1.2%), consistent with the strongest housing starts in 2025. The West (−8.0%) and Southwest (−10.5%) fell hardest. The South, the largest region at $465 million, declined 6.7% — but it is where the most shelf is changing hands.
Within the South, fiberglass batts fell 9.6% while mineral wool grew 11.5%. Johns Manville pulled back $37.6 million in the South across both retailers. CertainTeed entered at Home Depot. ROCKWOOL expanded at Lowe's. The brands gaining share are aligned to each region's growth material.
Two Retailers, Two Category Strategies
Home Depot and Lowe's are not just carrying different brands — they are building different categories. Home Depot's growth has moved to foam board, where Owens Corning (56%) and Henry (25%) control roughly 80% of a $222 million segment. Lowe's board business is $106 million and fragmented across Kingspan (36%), private label (18%), and Insulfoam (10%), with no national brand holding a dominant position.
The mineral wool gap is equally stark. ROCKWOOL does $78 million at Lowe's against $44 million at Home Depot. Mineral wool batts grew 14% at Lowe's but fell 4% at Home Depot. A manufacturer with a mineral wool program has a proven playbook at Lowe's and an addressable gap at Home Depot.
Datavations tracks every SKU, every store, every sale across 3,700+ insulation locations, giving manufacturers the granularity to see which materials are gaining at which retailer in which region — the level of precision that turns a $1.7 billion category decline into three distinct growth opportunities.
What This Means for Manufacturers
With housing starts down 7%, category growth will not come from demand. It will come from share and mix. Three openings stand out.
First, the mineral wool gap at Home Depot is addressable. ROCKWOOL does $78 million at Lowe's against $44 million at Home Depot — a proven playbook waiting to be applied.
Second, Lowe's foam board is open territory. Home Depot's board segment is concentrated behind Owens Corning and Henry. Lowe's is fragmented with no dominant national brand.
Third, Johns Manville's $37.6 million Southern retreat freed shelf at both retailers, and the brands filling it — CertainTeed at Home Depot, ROCKWOOL at Lowe's — are aligned to each retailer's growth material.
How big is the insulation category at Home Depot and Lowe's?
Residential insulation generated $1.7 billion across Home Depot and Lowe's in the trailing year ending May 2026. Home Depot holds roughly $1.02 billion (down 5.0%) and Lowe's holds $668 million (down 4.2%).
Why is fiberglass insulation declining?
Fiberglass batts still represent 61% of insulation sales but gave back $84 million year over year. Units per store fell 12–18% while prices rose, indicating demand softness rather than a shelf issue. Mineral wool and foam board are absorbing part of the shift.
Which insulation brands are growing?
ROCKWOOL grew 21% to $78 million at Lowe's, driven by mineral wool expansion. CertainTeed surged 162% at Home Depot, building a Southern fiberglass business from near zero. Owens Corning is shifting its Home Depot mix from batts toward foam board.
What is the difference between Home Depot and Lowe's in insulation?
Home Depot's growth has moved to foam board, where Owens Corning and Henry control 80% of a $222 million segment. Lowe's growth is in mineral wool, where ROCKWOOL holds $78 million and is adding stores at a 20% rate. The two retailers are building fundamentally different category strategies.
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