Thread: Sagging floors in 95yo home

I've inspected some old home. This being the oldest. The ceiling in the kitchen and dining rooms always seem to have a very good sag. Very noticeable, on these old balloon framed homes, how much bearing is there for the joists? Cuz the doors on second floor are racked so bad that only Dr Suess could built it.
The home is built very solid, big wood, diagonal sub flooring etc...

So the question may sound like..' At what point will that style of home cave in due to sag...I see old homes with his sag...normal. ?

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Originally Posted by Stephen G

I've inspected some old home. This being the oldest. The ceiling in the kitchen and dining rooms always seem to have a very good sag. Very noticeable, on these old balloon framed homes, how much bearing is there for the joists? Cuz the doors on second floor are racked so bad that only Dr Suess could built it.
The home is built very solid, big wood, diagonal sub flooring etc...

So the question may sound like..' At what point will that style of home cave in due to sag...I see old homes with his sag...normal. ?

It depends!

I doubt anyone could give a one size fits all answer.....🙈🙉🙊

Hey Scott,

Nor am I looking for one. With this style of build were the joist sitting on better then 1.5 inches bearing surface. If not then this might be a pretty big problem. If they were attached in a manner I'm not familiar with, I'm almost 50, kinda short about 70 years on this one Then it might be common but still need a struct eng.
I called it all out, took me half a day to inspect and about that to write it. It was a history lesson as I walked through it. But why am I seeing more like this, with a very noticeable sag. No obvious signs of wall removal. Have you guys seen this enough to say its common, yet, needs further.....

Just thinking out loud

I've seen it many times. Most of the time there's a chimney in the center of the home that has settled over the years and brought the upper floors with it. Generally pretty normal if the posts and beams are still intact and supporting the joists.

I've also seen, many times, where the bottom of the support post have rotted and caused similar sagging. So keep your eyes out for that.

In general, in a balloon framed structure, the floor joists rest on ledgers, or ribbands, that are usually let-in to the studs at each floor. Mostly of 1by material, the bearing is between 1 and 3/4 inch. Sometimes the rib and is nailed on the face of the joist and covered by a cover plaster ceiling/wall interface. The joists not only rest on this rib and, but also should be nailed to the side of the studs. This type of construction needs fire blocking at each floor to slow fire propagation in the wall space from basement to roof.

Dependent on age, it is common to see the floors slope towards the centre of the house (usually the centre hall staircase). The opening in the floors around stair cases most likely are not framed like todays so this exacerbate the problem.

If the floor is sound... I usually move up and down in place to see if the there is any springiness in the floor (you will feel it and/or you will hear the china rattling in the dining room hutch).

Remember the construction is old and most likely over the decades previous owners have modified the framing.

Also many times the basements are or were damp with dirt floors and there can be a lot of wood rot in the timber flooring, beams and columns in contact with dirt floor.

Again, columns will need replacement as well as some floor joists or beams dependent on condition. It is common to see sistering of floor joists, or additional beams added under floor joists in the basement areas.

Then again many of these old homes have done their settlement and I would also be inclined to ask your clients what their intentions are for the house renovation wise to give you a better idea as to guide them with your findings.

As to fire stopping that is inherent in the design for the period and it would be impossible to add it, unless major renovations are planned. The joists in the basement can be pocketed into the stone rubble foundation as well, and those ends can be subject to deterioration. Or in some instances if there is crawlspace the mud sill can be rotted out and crushed, and there will be a distinct floor drop on the floors at wall intersections.

Many folks can appreciate they are not buying a new house and accept the oddities, other times those not familiar with old houses will be turning their back on it.

The idea at least with an old house is to keep things in perspective given the age, construction techniques for your client and what improvements/repairs are required.

While steel fails in dramatic fashion, wood fails slowly and gives you notice.

In balloon framed structures such as these, the floor joists usually run gable to gable. Sometimes the center girder is notched and the joist is shouldered and placed in the notch, held by one or two hand cut 20d nails. At the gables the joists are side nailed into the studs and rest on a ribband that was typically a 1x4 let into the studs.

The shouldered joist, often 1/2 the depth of the member, often is a point of failure where the member would split along the grain. This typically occurs where the joist is undersized for the load. Floor joists are often undersized and lead to a bouncy floor.

The issue with sagging floors in the center is often due to the girders being undersized for the load. When calculating the loads being carried by the girders I typically start with attic and work my way down. By the time you get to the basement girder, you realize it should be an 8x14 beam if there is any span greater than 6 feet. That's not often what you find down there (in my own home, the attic beam is 10x10 while the second floor "beam" is 6x5).

The basement is often the culprit, although the actions of previous homeowners may be as well. Posts bottoms often rot, causing the structure to sag. Homeowners remove posts and knee braces in an attempt to make the space more open or locate mechanicals. Sometimes the chimney has a corbel on which the center girder is supported and the chimney settles or the lime mortar from the often unlined chimney deteriorates, causing the chimney to become unstable.

Sagging floors typically has nothing to do with bearing at the ends of the joists. The sagging (deflection) is usually greater because the wood was not kiln dried (wet wood deflects more than dry wood) and wood continues to deflect over time (this is known as creep). It is also not uncommon for the joists to be undersized by present standards. If the joists are adequately sized then the potential for failure is very low, other than cracking that may occur at knots.

If the joists look fine and are sized ok, typically I am not concerned. When you cannot see the joists, then it is harder to say what is acceptable. Heavy bathroom tile, single joists at the ends of stairway headers, and possible notches in floor joists for drain pipes can also be factors.

Many an old structure may not have rough sawn joists and the floor framing will consist of hewn logs laid on their sides which renders the logs more susceptible to sag.