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9.5-in x 2.5-in x 24-ft BLI 40 I-joist

3.4

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Designed for longer spans, BLI Joists unlock new design possibilities, creating open and spacious interiors without compromising structural integrity. Their advanced engineering ensures exceptional load-bearing capacity, guaranteeing both durability and safety.

Lightweight and easy to handle, the I-shaped configuration allows for longer spans and more load-carrying capacity than dimensional lumber
Manufactured with Machine Stress Rated (MSR) or Laminated Veneer Lumber (LVL) Flanges and an enhanced OSB Web
Low moisture content means greater dimensional stability resulting in quieter floors and fewer costly callbacks
Wide flanges provide more support for floor sheathing and more surface area for nailing, saving time and money
The following factors will affect floor system performance: span, spacing, joint series and depth, type of subfloor used, and how it is attached, elevation of supports
Additional factors that will affect floor system performance: type of support, presence of gypsum wallboard underneath, size of room and contents the floor is supporting

Prop 65 Warning(s)

General
Type	I-joist	Material	Wood
Green or Kiln-Dried	Kiln-dried	Series Name	BLI 40

Dimensions
Common Length (Feet)	24	Common Width (Inches)	2.5
Actual Length (Feet)	24	Width Measurement	2.5
Web Thickness (Inches)	.375	Actual Height (Inches)	9.5
Common Thickness (Inches)	1.5	Common Height (Inches)	9.5
Thickness Measurement	1.5

Certifications
CA Residents: Prop 65 Warning(s)	Prop 65 Warning(S)

Warranty
Warranty	Limited lifetime

Compatibility
For Use with Floors	Yes	For Use with Ceilings	Yes

Miscellaneous
UNSPSC	30103600

Check out the Best Selling Joists on Lowes.com

Review

3.4 out of 5

10 Reviews

4 Star

2 Star

38% Recommend this product

Ratings may include incentivized customer reviews.

10 Customer Reviews

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You need two people

Would Recommend

it is sturdy and light. Being light, makes it easy to work with.

JadiJanuary 29, 2026
From 9.5-in x 2.5-in x 16-ft BLI 40 I-joist Verified Purchaser

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Bad Joists

Would Not Recommend

This was the worst I have ever received. The joist where bowed and twisted which took me some time to get them straight to the ceiling. The joist itself was not glued correctly and was missing large section of wood. Again, these joists have been fabricated from the worst wood they could fined.

MikeDecember 3, 2025
From 9.5-in x 2.5-in x 20-ft BLI 40 I-joist Verified Purchaser

Was this Review Helpful ?

Poor quality

Would Not Recommend

Many of the I Joist had poor joints with many broken finger overlaps and gaps with no glue. Reported back to Lowes but never got a response back.

ScottJune 5, 2025
From Kiln-Dried I-joist Verified Purchaser

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make sure you measure your lumber.

Would Not Recommend

ordered 20ft material and reviewed 21ft boards. contractors charged me extra labor for cutting them down to 20 ft.

do it yourselfApril 15, 2024
From I-joist Board Verified Purchaser

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Good price, not very good quality

Would Not Recommend

I haven't built anything in a while but I was a little shocked at the poor quality of lumber used to make these trusses. The top and bottom 2x3 plates were essentially cull lumber quality. Large chunks missing and alot of tree bark still on the edges, causing a rounded over surface. Perhaps this is normal these days, however if I had seen this quality before waiting 2 weeks for delivery I probably would shopped around and paid a little more for a better supplier.

Richard DMarch 24, 2024
From I-joist Board Verified Purchaser

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Straight joist not square on ends.

Would Not Recommend

Service and order fulfillment timing was good, ends of the joist we’re roughly 1/2” out of square.

Wooden PilotSeptember 27, 2023
From 11.875-in x 2.5-in x 12-ft BLI 40 I-joist Verified Purchaser

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COMPARE PRODUCTS

		Name	Current Item 9.5-in x 2.5-in x 24-ft BLI 40 I-joist
		Ratings	10
		Material	Wood
		Actual Length (Feet)	24
		Type	I-joist
onCENTER9.5-in x 2.5-in x 30-ft BLI 40 I-joist	onCENTER14-in x 3.5-in x 24-ft BLI 80 I-joist	onCENTER11.875-in x 2.5-in x 24-ft BLI 60 I-joist	onCENTER16-in x 3.5-in x 28-ft BLI 80 I-joist	onCENTER16-in x 3.5-in x 16-ft BLI 80 I-joist	onCENTER11.875-in x 2.5-in x 26-ft BLI 60 I-joist	onCENTER11.875-in x 2.5-in x 30-ft BLI 60 I-joist	onCENTER16-in x 2.5-in x 22-ft BLI 60 I-joist	16-in x 3.5-in x 40-ft BLI 80 I-joist
10		10	10	10	10	10	10	10
Wood	Wood	Wood	Wood	Wood	Wood	Wood	Wood	Wood
30	24	24	28	16	26	30	22	40
I-joist	I-joist	I-joist	I-joist	I-joist	I-joist	I-joist	I-joist	I-joist