It is not unusual to find sap in the attic wood of an historic house. This house was built in 1870.
There are many, many more trees in the country now than there were 1870. Why? Husbandry.
But the pine wood used now is different. Pine trees in that era, that were used for construction, grew naturally and were older than pine trees used now. So they grew bigger! There was more heart wood in the tree.
Heart wood is the darker wood in the center of the tree. Heart wood was the more desirable wood selected and used for furniture, woodworking, and construction.
In Virginia in 1870 the most abundant pine trees, and the most popular used for woodworking and construction, were the Virginia and Loblolly pines. They both grew to 100'+. They produce good, straight trunks that were efficiently used for wood needs.
Lumber yards carefully planned how to use the logs for cut wood boards and beams.
And depending on where the wood was used the grains created boards of different strengths and tendencies.
Sap flows through the outside areas of the tree called sapwood.
Sapwood is made up of actively-growing cells that trap water and nutrition derived by the roots from the ground. The sapwood conducts water and nutrition up through the tree and out toward the branches. Nutrition (sap), which is sugar, is pushed through the cells by pressure created by carbon dioxide.
But after the wood is harvested and dried in kilns, and then used in construction, carbon dioxide is no longer present.
When wood was selected, the sapwood was less desirable.
But if it was used in construction, then exposed areas like the attic would be where it would most likely be put.
If sap is present, and in this 1870 house I saw a few members of sappy wood, what makes the sap move since there is no carbon dioxide to create the pressure necessary to push the sap?
This wood has had 140+ years of hot and cold seasonal cycles! That causes expansion and contraction of the wood. And if there is sap present in the wood, such natural thermal change certainly creates enough pressure and movement to push the sap!
This board was very colorful indeed. And yes, it smelled like pine!
My recommendation: you might see sap in pine wood used for decks. I do all the time. But sap can also be seen from time to time in wood trim used inside the house. It will bleed through paint, and is usually seen as knots or lines. This is quite a natural process. But hopefully the trim on the door to the bedroom doesn't look like the board above!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560