Hi Sally and Bill,
Welcome!
We may be to help you, but we also may need more info to help you better.
When you say, "the floor is going to need to be replaced." are you referring to the "entire" floor in the camper or only a portion of it, and if a portion, how much and where on the floor plan?
Assuming you feel the floor is soft, does it have water damage (that you know of) or just structural damage?
I have rebuilt many floor portions in the Sunlines that had wooden floor joists; the walls in all these cases also had water damage which is how the floor rotted out. I have lots of pics and posts showing this and am glad to share. But, your Advancer was made differently than the wooden framed Sunlines. Yours I "believe," was Sunline's first start into making a composite section floor of aluminum, foam board, and then luan plywood on top.
Some of the Advancers did have wooden floor joists; then they went to the aluminum sandwich. You will have to sort out which vintage you have. The year 2000 Advanver sales brochure in our files section discusses the new aluminum frame so you might have the metal.
To get you started, here are three posts from other members who did floor repairs on their advancers
https://www.sunlineclub.com/forums/f...n-17728-2.html
https://www.sunlineclub.com/forums/f...cer-16265.html
https://www.sunlineclub.com/forums/f...cer-14798.html
If you are doing an entire or partial floor, you might create a wood floor joist structure and then new plywood on top. But this kind of decision is premature until you and we know more about "why" the floor needs to be replaced. Water damage in the walls may suggest a different approach for the walls and the floor.
Give us more to go on, and we can help better.
Hope this helps
John
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Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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