You are here:

Civil Engineering/Span and Spacing with pine and plywood


QUESTION: I am providing a 30' x 50' x 46" deep portable pool for temporary use (1 week) at an exposition.  The installation is outdoors, and the surface is 10" off level from corner to corner.  Manufacturer specs say that I need the pool no more than 2" off level.

I will build a flooring under the low corner (and encompassing 70 of the pool area), using 1" plywood flooring supported by pine 2x4s which are shimmed.

Considering the weight of the water, and kayaking activity in the pool, what kind of spacing do I need, and what should the maximum span be on the 2x4s?

As the slope gets closer to the flooring, 2x4s become to large and I am forced to use 2x4s laid on their sides (1.2" high).  What should the span be at that point?

ANSWER: Dear Don

Please give me a drawing even by free hand to let me know more details about your problem..


---------- FOLLOW-UP ----------


QUESTION: These 2 photos should show what we did in 2013, when we put a similar 30x50' pool in the same location.  The problem for 2014 is that the pool is now 46" deep instead of 20" deep.  Because of that, I will need to make it more level (I allowed a 4" slope last year- basically the area where I did not build up flooring), and will need to greatly strengthen the framing below.

As you can see, the framing from 2013 was 2x4s on 24" spacing, shimmmed every 5-6', and with 1" plywood flooring.

I realize that I will have to greatly beef this up, but by how much?

pool supports
pool supports  
Dear Don

As I calculated you can use the same support and the same distance provided that you use a 2x2 in wooden stick on the middle of the support along the sides of the pool and on the corner put an inclined support restraing the middle of the support to the basement. I sent a picture very quickly made for your help.


Civil Engineering

All Answers

Answers by Expert:

Ask Experts


Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

Sinam Consulting Engineers Co.

Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

©2017 All rights reserved.