Joist Support Frequently Asked Questions

Watch our Adjustable Joist Support AJH38G (USA) Installation Video


Can I use the Adjustable joist support with steel joists?

We have not yet found a steel joist of the right thickness, so haven't tested this as yet. There doesn't appear any reason why it shouldn't work.


Can I use the joist support cradle without the base-plate and just fix this to my concrete?

Yes, the joist support component is designed to be able to be used on its own in areas that warrant this. The ribs in the bottom of the joist support will still keep the joist off the concrete by approx  1/4 inch. You do of course lose the "adjustable" aspect of the product.


Can I purchase the joist support cradle separate from the base plates?

No, the products come as a pair in boxes and cannot be purchased separate from each other.

Do all the nuts, bolts, washers etc come included with the Adjustable joist supports?

No, you must purchase these items separately as the height of the deck off the concrete will govern what length bolt will need to be used.

Each Adjustable Joist Support ( joist holder + base plate) requires 2 x 3/8 inch Hex Head Bolts, 4 x 3/8 inch Nuts & 2 X 3/8 inch washers, 1 x 1/2 x 2 inch long Galvanised screw anchor or similar.

What are the minimum and maximum length Hex Head bolts can I use?

Minimum 2 1/2 inch long and Maximum 5 inch long galvanized Hex Head bolts.

How is the product packaged?

The product comes in boxes containing 24 joist supports and 24 base plates.click here to see photo  Bolts, nuts, washers etc.  are purchased separately from your hardware store/merchant depending on what height you want to achieve.

Do I have to use the two washers for every adjustable joist support?

Yes, the washers are very important and form an integral part of the system.

What size galvanised screw anchor should be used to hold down the base-plate?



AJH38G - 1 x 1/2 inch x 2 inch long Galvanised screw anchor or similar.


What galvanising standards is the Adjustable joist support galvanised to ?

KlevaKlip Joist Supports and Base Plates have been hot dip galvanised in accordance with International Standards ISO 1461:2009 and USA Standards ASTM A123.

What is the Load bearing capacity of the Klevaklip Adjustable Joist Support?

This has been independently tested to support a load bearing capacity of 60 PSF when used at the recommended joist spans listed below.

Can I install the Adjustable joist supports over brick pavers?

No, this is not recommended as the pavers do not have adequate structural stability.

How to calculate how many Adjustable Joist Supports are needed for your deck?

We quite often find that people have miscalculated the number of adjustable joist supports required for their decking area. We believe the main cause of this is that people work out the length of their joists, and simply divide by the "support spacings" (taken from our span table) they have decided on between the supports - eg - having a  9ft 10 inch length joist with spacings of 3ft 3 inch to give 3 supports. Wrong! - This does not take into account the initial support at the start of the joist.

Therefore, the correct answer would be 4.

Similarly, when working out the number of joists required, you need to work out the number of "joists spacings" along your deck and remember to add one for the initial joist.

So, to finalise the number of supports you will need for your deck, multiply the number of joists on your deck by the number of supports to be placed along your joists. This should give you an accurate answer.




How regular along my joists do I need to put the AJH38G (USA) Adjustable joist supports?

See our span table below

Span requirements for base-plate positioning all based upon "continuous span" with joists at 16 inch between centre's.

All joists should be pressure treated for outdoor use.

Joist Size Recommended Span (feet) Maximum Span (feet)
 2 x 4 inch 3 ft 3 inch 4 ft 11 inch
*2 x 6 inch 4 ft   6 ft

* Joist span limited by lateral loading on bolts

What length bolts do you require for AJH38G (USA)?

Note: All measurements based on using Galvanised long-threaded hex head bolts.

Hex Head Bolt Length Min Height to Bottom of Joist Max Height to Bottom of Joist Min Height to Top of 4/6 inch Joist Max Height to Top of 4/6 inch Joist
2 1/2 inch 5/8 inch 1 inch 4 1/4 / 6 1/4 inch 4 1/2/ 6 1/2 inch
5 inch 3/4 inch* 3 1/4 inch 4 1/2*/ 6 1/2 inch 6 1/2 / 8 1/2 inch
**No Bolt 1/4 inch   3 3/4 / 5 3/4 inch  


* If using long bolts at low heights, to prevent the bolts protruding past the top of joist, the end of the bolt will need to be cut off.

** When Using Joist Support Only.


What are the dimensions of the AJG38G(USA) KlevaKlip Adjustable Joist Support Base Plate & Support?