Bottom Plate Fixing and Hold Downs

Bottom plate fixing of timber and steel framed tiny houses on wheels is very important to resist wind up lift and transportation movements. Our trailers generally use RHS 75 x 50 (rectangular hollow section) down the length of the trailer and 50 x 50 at the front and back. There is a number of different fixing options available to suit construction method, tools available and material supply.

General construction method is usually level and secure trailer, lay floor and stand frames. Frames can be tacked with nails or screws to ensure correct position before hold downs added.

Bolt through

M13 Hole is drilled through bottom plate, flooring, and trailer steel. Generally, a M12 galvanised steel bolt is added to sandwich the three components using large washer over the bottom plate. Location nearer the stud is better. A long series drill bit may be needed.

Stud Anchor

L shaped bracket screwed to stud and bottom plate using self-drilling screws. Works better using steel framing and best to ensure bottom plate screws penetrate the steel of the trailer. Can be used as intermediate anchors for speed of install between important bracing anchors near openings for example.  This method works well at the front and back of trailer where bolt through is not possible.

Bracing Anchor

Designed for bracing elements using GIB here in NZ using the trade name Handibrac. Can be used well in this application as holds bottom plate as well as stud. Drill hole and bolt same as bolt through method. Use steel self-tapping screws or timber screws to secure bracket. Brackets can be brought without screws as maybe supplied screws not be right for application.

Brace Straps

Steel straps have a series of holes to fix nails or screws into stud, bottom plate and trailer joist. Self-drilling dome head screws can be used to reduce thickness on trailer joist or when using steel framing. Nails can be used on timber frame.    

A hold downs should be added next to any opening and in all four corners. As a general rule of thumb every 1200mm along a wall and where appropriate. Combination of the above methods can be used. All above products generally available off the shelf at any good merchant.

This is a general guide only please refer to NZ3604 , NASH and manufacture information.