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Imus Cap

Imus Cap is a patented, easy to install joist and beam cap designed to protect your wooden deck structure from water damage and rot. Imus Cap is made of bonderized metal with Imus Flex pressure-sensitive butyl rubber waterproof adhesive.

Deck Size and Protection Calculator


Imus Cap is one of our solutions to Protect your deck structure™.

Imus Cap logo Imus Seal logo
Imus Cap Imus Seal 1-5/8 inch Butyl Adhesive
26 gauge bonderized metal
62.5 mil butyl membrane
Multi-layer laminate HDPE film
12 mil butyl membrane
Diverts Water from Joists and Beams
Seals Decking Screws
Easy to Install
Provides a Barrier Between Metal and Wood
Protects Treated and Non-Treated Lumber
1-5/8”: $1.87/ft.
3-5/8”: $3.12/ft.
1-5/8”: $0.40/ft.
4”: $0.72/ft.
6”: $1.00/ft.
Learn more



Imus Cap logo

Want to prevent deck rot? Protect your deck structure™ with Imus Cap.

Imus Cap was invented by a contractor and is the joist cap trusted by building professionals and homeowners to extend the life of deck structures.

  • Imus Cap diverts water away from your joists and beams.
    26 gauge bonderized metal resists rust, can be painted, does not need to be pre-drilled for decking screws, and can be cut with aviation or tin snips.
  • Imus Cap seals your decking screws.
    Imus Flex butyl rubber waterproof adhesive membrane protects the top of your joists and beams from moisture. It works better in extreme temperatures than asphalt-based adhesives and does not release asphalt odors.
  • Imus Cap is easy to install.
    Simply peel and stick to apply Imus Cap to your deck structure.
  • Imus Cap protects treated and non-treated lumber.
    Compatible with all deck materials including pressure-treated wood and composite products.




Size: 1-5/8" 3-5/8"
Imus Cap 1-5/8 inch Imus Cap 3-5/8 inch
UPC: 860001190410 860001190427
Width (inside): 1 5/8 in. 3 5/8 in.
Length: 95 in.
Weight: 1.8 lbs. 3.6 lbs.
Composition: 26 gauge bonderized metal with Imus Flex 62.5 mil butyl rubber membrane and a release liner
Packaging: Packaged with red end caps for safety and convenience
Made in the U.S.A. 🇺🇸






Imus Cap Press

"Imus Cap protects joists and beams from moisture with a paintable metal top layer and a waterproof adhesive"

Professional Deck Builder magazine



Imus Cap on Social





Frequently Asked Questions & Answers

Is Imus Cap compatible with my deck surface material?
Yes, Imus Cap works with naturally durable wood (e.g. redwood, cedar), pressure treated timber (e.g. southern yellow pine), exotic tropical hardwoods (e.g. ipe, teak, tigerwood), thermally modified wood, wood plastic composite (e.g. Trex, Monarch, TimberTech, Veranda), or plastic (e.g. polystyrene, PVC).

Will Imus Cap corrode when in contact with treated wood?
No. Imus Cap is made of bonderized steel, also referred to as paint grip steel, which is G90 hot-dip galvanized steel that has been put through a phosphate bath and a chromate dry. Bonderized metal withstands corrosive chemicals commonly used in pressure-treated lumber like alkaline copper quaternary (ACQ) and copper azole (CA).

How is water kept from entering the joists where the deck fastening screws penetrate the metal cap?
Imus Flex self-adhered butyl rubber flashing membrane seals around fasteners.

Are self-tapping screws required for installation?
No, standard decking screws can penetrate 26 gauge metal. A demonstration video is in this blog post.

Should Imus Cap be overlapped or butt together?
We recommend butting pieces together (butyl membrane will fill gaps when being fastened down). Overlapping could result in uneven decking surfaces.

How are “T” ends or joints protected where joists and beams meet?
An edge can be cut and raised to overlap the other cap as shown in the diagram below.
Imus Cap joist to beam installation

Can Imus Cap be used to protect wood structures other than decks from rot?
Yes, Imus Cap can be used on stair stringers, trellises, pergolas, exposed exterior beams, and more.

Are there retailers that stock Imus Cap?
Yes, here is a map of our retail partners. Imus Cap is also available on Amazon.

Can I calculate how many lineal feet of Imus Cap my deck needs?
Yes, you can calculate your deck square footage and estimate how much Imus Cap it will need with the Deck Size and Protection Calculator.



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Customer Reviews

Based on 8 reviews Write a review

Customer Reviews

Based on 18 reviews

Just what I was searching for. Just today cut and installed the caps. Easy to cut and apply


Happy with the product

Not just for new deck construction

I had to tear off the old cedar decking from my deck. As the joists are also cedar some had some surface rot and are full of old nail holes. Still structurally sound but would have continued to deteriorate without placing the Imus Caps over them. Hopefully I've extended the life of my deck joists for another 30 years.

Great Product!

Thanks for developing this product! It was easy to install and cut.
It will be a great addition to my business and customers need this!
Thanks again,
Curt Largent

Alternate Use

I bought one stick in order to protect a cantilevered ledger board that is part of my aluminum/vinyl pergola (Heartland Pergolas). The 2 x 8 beam extends out about 3 ft from the house corner and therefore is not flashed. I used the cap to provide protection for this one wood piece on the pergola. I painted it to match and it looks great. The good thing is that this board should now last the life of the pergola since it won't have rain and snow soaking into the board. If I had done a wood pergola, this product would have been perfect protection for all the joists, which was the point of failure on the previous wood one. I wish I had known about it (if it existed) 20 years ago when we had our deck redone.