I want to replace the small square access hatch to my attic with an attic ladder.

Problem is that the 22.5" x 54" rough opening frame (made of 2x6 lumber) has to run across two of the existing ceiling rafters. The following picture shows the situation:

View attachment 699448

I can do this myself, but at 73 now I'm not fond of working in the attic heat anymore. So, I hired a local framer to do this for me. He's hesitant to do the job because of the short sections of the two ceiling rafters that have to be cut out. (I actually think he's more concerned about liability issues for him if he does it.)

Note that there is also one load bearing wall that can be used to add a brace to the trusses if necessary, as shown in this picture:

View attachment 699449

So, the question is: If I cut these two short sections of the two rafters out and install the 2x6 lumber frame for the rough opening where I show it in the picture, will this be OK? Will the modified area be strong enough to both support the weight of the attic ladder AND not cause a problem with the trusses holding up my roof?

Thanks in advance for any advice.

No You have trusses and you never ever cut trusses, if you can find a different location, you just can not put it there.

 

Can you not rotate the opening 90º and frame a longer opening between the trusses? What's the truss spacing? The HVAC platform may be a problem here.

 

No, it can't be rotated. This is a narrow upstairs hallway location that is only 3' 10" wide. So, the ~2' x 4 &1/2' stair won't fit sideways.

I understand that you certainly can't cut the angled truss members that are directly in contact with the roof. But, to me, the area I'm proposing to install the attic stair rough opening 2x6 frame will actually be stronger with that 2x6 frame installed in place. If you examine the stresses that are applied, any stresses along the longitudinal axis that was previously applied to those "missing" sections will be handled quite easily by the new 2x6 lumber rough opening frame now supporting them.

It's not like I'm removing those two sections of rafters and NOT replacing them with a structure of equal strength to absorb the longitudinal stresses. I am.

 

Even this tight space ladder is to wide.

Fakro Scissor Attic Ladder - 27.5" x 31.5" - Steel - Gray

 

Unfortunately, still too big. The first rafter that has to be cut is only 24" from the ladder hinge.

Thanks for the idea.

 

They do make one for a standard access
FAKRO LST 66875 Insulated Steel Scissor Attic Ladder for 22-Inch x 31-Inch Rough Openings

 

Yup, this one will fit sideways in the hall. Never knew they made attic ladders like these.

Thanks much for the information!

 

I'm going to follow up with a stern warning because I'm not sure you've accepted putting in a small ladder to fit between the trusses without altering them, or if you are going to continue to be stubborn about cutting some trusses because you think you know what you are doing and read a couple scientific sounding terms ("longitudinal stresses").

There is no way around it - DO NOT CUT ANY OF THE TRUSS WOOD MEMBERS IN ANY WAY. THEY WILL FAIL. Period. Exclamation Point.

Your concept of what a truss does and why it looks like that is all wrong. There are no "rafters," the web chords (angled pieces in the middle) are not supporting "rafters," the bottom chord is very important. When you design a truss, each wood section between each metal plate connection is designed for a specific load and it transfers everything, in concert with all the other chords of the truss, over to your 2 bearing points, which are at your exterior walls. All of those chords (the top, web, and bottom chords) are placed at very specific dimensions for those loads and each one has a role. If you remove any 1 chord, you have messed up the tension vs compression loads, and altered the joint capacities. And you cannot bastardize the path of the loads heading to the 2 exterior walls by introducing other bearing points in the middle of it. None of this is guessed at, it is all math. That is how you can use a dainty 2x4 toothpick structure that resists all those roof and wind loads.

Your proposed 2x6 hole frame does nothing but mess up the bottom chord and transfers loads to adjacent trusses that haven't been designed for that. People are always misguided because they build something in wood, screw or nail the heck out of it, then push/pull/hang on it and wow, it holds them! Unfortunately, your tugging and body weight is nothing compared to a snow load, wind loads, and moments.

If you need a larger ladder for potential HVAC equipment access, put it somewhere else in the house, between the trusses and leave the trusses alone.

 

Agree 100% with everyone above. Never ever ever ever ever cut a truss in any way shape or form. I could not think of many worse things you could possibly do to your home! As a carpenter and framer for 18 years you must truss me! If you chose to do this, I will attempt to find your IP address. Haha just messing with you...but no no no.

 

I think the point has been made abundantly clear, but I'll say it again, anyway. Do not cut any members of a truss. You might find a structural engineer willing to design a solution that transfers the forces around the opening, but the you won't like the fees or the cost of the construction, if you can even find one that would take on the project. I know I wouldn't.

 

Calm down people!

The Fakro 22 x 31 steel scissors ladder will suit just fine. I'll use that.

Thank you all for your experience on this issue.

 

Werner Easy Stow Loft Ladder - 3 Section
This is Werner brand which I have found to be good. It is aluminum which I love light weight. Costs about $109 and appears to fit your space. It has a handrail also.
Werner 3 Section Hideaway Loft Ladder 76013. This loft ladder has been manufactured from aluminium. It is suitable for heights up to 3m (9’10”). With a Spring assisted ’Easy Stow’ system it gives total control when lowering or stowing the loft ladder. In-loft handrail for added safety when entering or leaving the loft. This Pack includes all components and easy to follow instructions. Features: Suitable for heights up to 3m (9’10”).
Load Capacity: 331 lb
Material: Aluminum
Special Use: Attic

 

Need to double up the joist along the sides, double block top and bottom, then block between double joist and next joist on both sides