FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Gapping composite decking?

BillHartmann | Posted in General Discussion on August 1, 2009 07:33am

I was looking at a high end remodel job that the HO decided not to move into and it is for sale.

I was there with the buyers agent, buyer, and home inspector for a 2nd look at some problems with the house.

I noticed one thing that was not one of the problems, but I question if it is a going to be a problem.

They have a composite decking on a covered deck, but which is well exposed to the weather. The deck is only about 8 ft deep. And the decking was run parallel to the house, which is normal.

And they installed soffit material on the underside of the deck. That is one of the problem areas.

But what I noticed was that the decking material had been run tight together. And I did not remember seeing any fasteners, but there might have been. But I thinking that they used hidden fasteners.

I don’t know the brand, but it is hallow with 3 channels extruded in it.

Now this was a warm day, but not overly hot. It was 82 yesterday, but the average is 89 and low to mid 90’s is not uncommon and the record is 109.

My question is does this stuff need expansion room and how much.

.
William the Geezer, the sequel to Billy the Kid – Shoe
Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. User avater
    kmsbc | Aug 01, 2009 10:05pm | #1

    Short answer - Yes.

    If you can determine the brand of decking, go on-line to get a copy of the installation guide.  Trex requires 1/4 - 3/8 inch spacing between pieces. 

     

  2. KenHill3 | Aug 01, 2009 11:33pm | #2

    Wow. Soffit installed below. No gapping. Problems.

    What idiot did this?

    The Woodshed Tavern Backroom

    The Topics Too Hot For Taunton's Breaktime Forum Tavern

  3. john7g | Aug 02, 2009 12:23am | #3

    According to al the MFG instructions I've seen yes it needs a gap.  But I've done a little section on my own using composite from Lowes butted tight together, in fact cut a rabbet in the edges to make a lap joint so there's actually a negative clearance.  Installed in the heat of summer and the 2nd year (or is it 3 now?) and have had no issues.  I'm probably going to do the same for the back deck in the next month or so since I like the look.  I wouldn't do this for a customers deck though since it does void the warranty.

    On the deck you looked at, if there were no buckling issues I don't see how it could be a deal breaker other than not being able to get a warranty service on it, but do you have all data required to get any type of warranty service on it in the 1st place? 

    1. Snort | Aug 02, 2009 01:52am | #4

      I've seen a tight trex deck hold water, kids loved it!http://www.tvwsolar.com

      We'll have a kid

      Or maybe we'll rent one

      He's got to be straight

      We don't want a bent one

      He'll drink his baby brew

      From a big brass cup

      Someday he may be president

      If things loosen up

      1. john7g | Aug 02, 2009 02:28am | #5

        like a pond?  what caused it (other that not gappingit)?  poorly sloped/undersized joists or..?

        1. Snort | Aug 02, 2009 04:09pm | #7

          No slope, up against the foundation on 2 sides, and undersized joists... had everything going for it...same guys put in another, and spaced it with speed squares... different brands at each end... who would have thought they were different thicknesses? Over 30' it added up. Same deck, they used the hidden Deck Master system. Most of the screws into the trex were overdriven... from the top it looked like trex with zits<G>http://www.tvwsolar.com

          We'll have a kid

          Or maybe we'll rent one

          He's got to be straight

          We don't want a bent one

          He'll drink his baby brew

          From a big brass cup

          Someday he may be president

          If things loosen up

    2. User avater
      BillHartmann | Aug 02, 2009 05:37am | #6

      "On the deck you looked at, if there were no buckling issues I don't see how it could be a deal breaker other than not being able to get a warranty service on it, but do you have all data required to get any type of warranty service on it in the 1st place? "Well in this case I am not responsible for anything other than giving an opinion. Other than that I know nothing, I see nothing.I would like to see it was a little hotter. It is suppose to 93 Monday so I will see if I can get access to it.I really don't know how it was constructed, but I am assuming that the joist run perpendicular to the house and you can see that the decking runs parallel.And while it is laid tight, it still allows some water to get through.I was asked about the soffit that they installed on the bottom. It is only supported on house side and the outside edges and is about 8 ft wide. So it bellies and hold water that drips out the seams..
      William the Geezer, the sequel to Billy the Kid - Shoe

  4. USAnigel | Aug 02, 2009 04:51pm | #8

    I have used the brand you have there and it installs like T&G flooring without gaps and hidden fasteners. Mine was floorizon by timbertech. It still looks great after 12 years!

    Look closer and you will find small drainage "cuts" in the joint seam.



    Edited 8/2/2009 9:56 am ET by USAnigel

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

FHB Podcast Segment: Finding Hazardous Materials in a Fixer-Upper

Look closely at these common locations for hazardous materials in older homes.

Featured Video

A Modern California Home Wrapped in Rockwool Insulation for Energy Efficiency and Fire Resistance

The designer and builder of the 2018 Fine Homebuilding House detail why they chose mineral-wool batts and high-density boards for all of their insulation needs.

Related Stories

  • Podcast Episode 693: Old-House Hazards, Building Larsen Trusses, AI in Construction
  • FHB Podcast Segment: Finding Hazardous Materials in a Fixer-Upper
  • A Classic Paint Sprayer Gets a Thoughtful Refresh
  • Podcast Episode 692: Introduction to Trade Work, Embodied Carbon, and Envelope Improvements

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2025
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data